He is asking how he can be truly just in all things
Question

                my name is XXX i pronounced shahada like a year and a half ago.

1) can you be just with all of humanity? abu huraira reported a bedouin came to the prophet laysallam and said i want to be the most just of men. he said do for others what you would do for yourself and you will be the most just of men in the quran it mentions that if one cannot be just with a women he shouldnt marry her hence only marry one . so the question is can you be just with all of humanity or try to be?

2)this is for me since i dont feel im just / like when i see a creature i do what i can for it./like if i believe it has bad health i try to give it good health: ex: dog i try to give it good health by rubbing spinal cord but i feel i should be doing more since i would want more done for me... i come to think that im not being just with myself by worshipping allah alone and following his guidance.... your advice?
Praise be to Allah.
    Firstly: 

    It is good to see among people 
    one who loves to be just and is eager to do so, and is asking for more 
    details and how to achieve that. It is by virtue of justice that the heavens 
    and the earth are maintained, and justice is the foundation on which the 
    best interests of people and countries may be served. It is one of the most 
    important things that Allah has enjoined in His holy Book. Allah, may He be 
    glorified and exalted, says (interpretation of the meaning):

    “Verily, Allah enjoins Al-‘Adl 
    (i.e. justice and worshipping none but Allah Alone - Islamic Monotheism) and 
    Al-Ihsan (i.e. to be patient in performing your duties to Allah, totally for 
    Allah’s sake and in accordance with the Sunnah (legal ways) of the Prophet 
    SAW in a perfect manner), and giving (help) to kith and kin (i.e. all that 
    Allah has ordered you to give them e.g., wealth, visiting, looking after 
    them, or any other kind of help, etc.): and forbids Al-Fahsha (i.e all evil 
    deeds, e.g. illegal sexual acts, disobedience of parents, polytheism, to 
    tell lies, to give false witness, to kill a life without right, etc.), and 
    Al-Munkar (i.e all that is prohibited by Islamic law: polytheism of every 
    kind, disbelief and every kind of evil deeds, etc.), and Al-Baghy (i.e. all 
    kinds of oppression), He admonishes you, that you may take heed.”

    [an-Nahl 16:90]

    “Verily! Allah commands that you 
    should render back the trusts to those, to whom they are due; and that when 
    you judge between men, you judge with justice. Verily, how excellent is the 
    teaching which He (Allah) gives you! Truly, Allah is Ever All-Hearer, 
    All-Seer.”

    [an-Nisa’ 4:58]. 

    The shar‘i principle that is 
    based on the mercy of Allah, may He be exalted, and His will to make things 
    easier for people, dictate that the Muslim should obey whatever he can of 
    these commands. So he should attain justice in his own life, deal with the 
    people around him on the basis of justice, and interact with all other 
    creatures on that basis; all of that should be in accordance with what he is 
    able to do, for absolute justice belongs only to Allah, may He be glorified 
    and exalted. 

    Hence when Allah, may He be 
    exalted, enjoined fairness and giving full weight and measure – which is a 
    type of justice – He followed that with a statement that there is no blame 
    attached to that which is beyond one’s capability. Allah, may He be 
    glorified and exalted, says (interpretation of the meaning):

    “and give full measure and full 
    weight with justice. We burden not any person, but that which he can bear. 
    And whenever you give your word (i.e. judge between men or give evidence, 
    etc.), say the truth even if a near relative is concerned, and fulfill the 
    Covenant of Allah, This He commands you, that you may remember”

    [al-An‘aam 6:152]. 

    It says in Mafaateeh al-Ghayb 
    by ar-Raazi (13/180): 

    It should be noted that because 
    it is possible that someone may think that it is obligatory to fulfil the 
    command to the highest degree – which is very difficult when it comes to 
    justice – Allah, may He be exalted, followed that with something that spares 
    us this difficulty, as He says: “We burden not any person, but that which 
    he can bear.” End quote. 

    Al-‘Allaamah as-Sa‘di (may Allah 
    have mercy on him) said: 

    “and give full measure and 
    full weight with justice” means doing so fairly, faithfully and 
    completely. If you strive hard to do that, then “We burden not any 
    person, but that which he can bear” that is, only as much as he is able 
    to bear, without causing him undue difficulty. If a person is keen to give 
    full weight and measure, then some shortcoming occurs without any negligence 
    on his part and without him realizing it, then Allah is Pardoning and 
    Oft-Forgiving. From this verse and similar verses the scholars of usool 
    determined that Allah does not give anyone a burden greater than he can 
    bear, and in the case of one who fears Allah with regard to what He has 
    commanded, and has done all that he is able to in that regard, there is no 
    blame on him for anything other than that.

    End quote from Tayseer 
    al-Kareem al-Mannaan, p. 280 

    Al-‘Allaamah Muhammad Rasheed 
    Rida (may Allah have mercy on him) said: 

    “We burden not any person, 
    but that which he can bear” – this is a new sentence which explains the 
    ruling concerning the difficulties that may be faced by people of piety and 
    religious commitment when they are trying to be fair in measures and 
    weights, because being fair is something very subtle that cannot be achieved 
    every time you measure or weigh out something, unless you use scales such as 
    those used for weighing gold, which gives the weight to the accuracy of one 
    gram or less. To commit oneself to achieving that level of accuracy when 
    buying grains or produce is very difficult. This is a matter that may arise 
    in the mind of the pious person; he may wonder what the ruling is (i.e., how 
    accurate must one be?). The answer to that question came in this verse: 
    Allah does not burden any person but that which he can bear, so that there 
    will be no great pressure or hardship in seeking to achieve something that 
    is very difficult. Therefore Allah did not burden the one who buys and sells 
    the foods mentioned above, and similar items, by requiring him to weigh or 
    measure to the accuracy of one gram. Rather Allah instructs him to be fair 
    and just when weighing and measuring, whether he is doing it for himself or 
    to give to others, according to what is customary, so that he will be 
    certain that he is not being unfair by giving more or less than that which 
    is regarded as fair according to custom. 

    The principle of making things 
    easy and keeping the burden within the limits that a person could bear – 
    which dictates waiving anything that could cause undue hardship or 
    difficulty – is one of the strongest foundations of this sharee‘ah, which is 
    based on the foundation of truth and justice; there is no set of man-made 
    laws that could equal it. If the Muslims acted in accordance with this 
    principle, then their dealings and transactions would become proper and 
    would flow smoothly, which would create trust and honesty among them, and 
    they would offer an example for cheaters and corrupt people to learn from. 
    Their affairs would not have become corrupted and they would not have lost 
    trust among themselves, which was replaced with trust of the foreigners who 
    are aiming to control and dominate them, which is what happened when they 
    abandoned these principles and guidelines. As a result you now see some 
    ignorant apostates spouting nonsense and saying ‘our religion is the cause 
    of our backwardness and that led to others going ahead of us.’

    End quote from Tafseer al-Manaar, 
    8/168 

    Our advice to you is to do your 
    best to achieve justice in all areas of your life. So be fair to yourself by 
    focusing on that which will lead to salvation and victory in the hereafter; 
    avoid that which will cause you to slip and fall short, so that you will not 
    expose yourself to punishment. Be just towards other people by upholding 
    ties of kinship, treating people kindly and pardoning those who mistreat 
    you; love for them what you love for yourself of good. Be just towards 
    plants, animals and the earth by showing mercy and compassion, and avoid 
    causing harm. Then if Allah sees you doing this, He will reward you by His 
    leave as He, may He be glorified and exalted, says (interpretation of the 
    meaning): “Is there any reward for good other than good? Then which of 
    the Blessings of your Lord will you both (jinns and men) deny?” [ar-Rahmaan 
    55:60-61]. 

    Secondly: 

    With regard to the hadeeth 
    mentioned in the question, it does not have any saheeh isnaad (sound chain 
    of narrators) from the Prophet (blessings and peace of Allah be upon him) 
    and it was not narrated by any of the authors of the famous books of hadeeth. 
    Rather it was mentioned by al-Muttaqi al-Hindi in his book Kanz al-‘Ummaal 
    (16/127) where he said: 

    Shaykh Jalaal ad-Deen as-Suyooti 
    (may Allah have mercy on him) said: I found in the handwriting of Shaykh 
    Shams ad-Deen ibn al-Qammaah in a collection of his, (a narration) from 
    Abu’l-Abbaas al-Mustaghfiri: I went to Egypt, intending to seek knowledge 
    from Imam Abu Haamid al-Masri, and I asked him about the hadeeth of Khaalid 
    ibn al-Waleed. He told me to fast for one year, then I asked him again about 
    (that hadeeth). Then he told me its isnaad (chain of narration) from his 
    shaykhs, going back to Khaalid ibn al-Waleed, who said: A man came to the 
    Prophet (blessings and peace of Allah be upon him) and said: I am going to 
    ask you about what will happen in this world and the hereafter. He said to 
    him: “Ask about whatever you like.” … And among the things he asked was: I 
    want to be the most just of people. He said: “Love for people what you love 
    for yourself; you will be the most just of people.” End quote. 

    This – as you can see – is not 
    sufficient to prove that this hadeeth is sound, because the names of the 
    chain of narration going back to Khaalid ibn al-Waleed (may Allah be pleased 
    with him) are not mentioned. 

    It says in Fataawa al-Lajnah 
    ad-Daa’imah (4/454): 

    This hadeeth is not saheeh 
    because there are unknown narrators in its isnaad. End quote. 

    ‘Abd al-‘Azeez ibn Baaz, ‘Abd 
    ar-Razzaak ‘Afeefi, ‘Abdullah ibn Ghadyaan 

    Shaykh Ibn Baaz (may Allah have 
    mercy on him) said: 

    This hadeeth is fabricated and 
    its narrators are unknown. It is as if the one who fabricated it compiled 
    its text from saheeh hadeeths and the words of some of the scholars, and 
    some of its phrases are odd and are not in harmony with shar‘i evidence. 
    Undoubtedly the correct view with regard to the matters mentioned in this 
    hadeeth is that which is indicated by the saheeh hadeeths; as for this text, 
    it cannot be relied upon or quoted as evidence, because it does not have a 
    saheeh isnaad. 

    End quote from Majmoo‘ 
    Fataawa Ibn Baaz, 26/326 

    There is a sentence in this 
    fabricated hadeeth, that is proven in the saheeh report according to which 
    the Prophet (blessings and peace of Allah be upon him) said: “Love for other 
    people what you love for yourself, (then) you will be a Muslim.”

    Narrated by Ahmad in al-Musnad, 
    13/459; classed as saheeh by al-Albaani in as-Silsilah as-Saheehah, 
    no. 930. 

    It was also narrated from Anas 
    ibn Maalik (may Allah be pleased with him) that the Prophet (blessings and 
    peace of Allah be upon him) said: “No one of you (truly) believes until he 
    loves for his brother what he loves for himself.”

    Narrated by al-Bukhaari (13) and 
    Muslim (45). 

    And Allah knows best.