Narrating hadeeth with the meaning
Question

I sometimes advise the others when they do a mistake clarifying the evidence from the authentic ahadeeth of the prophet . Sometimes I forget the exact text of the Hadeeth and mention its meaning only or a part of it. Is this permissible, or considered lying about what the prophet said? I may hesitate to advise fearing this, I fear also by doing this I mislead myself or others, May Allah protect us from misguidance. What do you advise me in such a situation?.
Praise be to Allah.Firstly: 
Calling people to Allaah is one of the best and noblest of deeds before Allaah, may He be glorified and exalted. How could it be otherwise, when this is the role of the Prophets and Messengers whom Allaah chose from among His creation, and of those who inherited their role, namely the scholars and daa’iyahs? Allaah says (interpretation of the meaning): 
“Say (O Muhammad صلى الله عليه وسلم): This is my way; I invite unto Allaah (i.e. to the Oneness of Allaah — Islamic Monotheism) with sure knowledge, I and whosoever follows me (also must invite others to Allaah, i.e. to the Oneness of Allaah — Islamic Monotheism with sure knowledge). And Glorified and Exalted be Allaah (above all that they associate as partners with Him). And I am not of the Mushrikoon (polytheists, pagans, idolaters and disbelievers in the Oneness of Allaah; those who worship others along with Allaah or set up rivals or partners to Allaah)”
[Yoosuf 12:108]
Allaah, may He be glorified, praises those who follow that path, as He says (interpretation of the meaning): 
“And who is better in speech than he who [says: ‘My Lord is Allaah (believes in His Oneness),’ and then stands firm (acts upon His Order), and] invites (men) to Allaah’s (Islamic Monotheism), and does righteous deeds, and says: ‘I am one of the Muslims’”
[Fussilat 41:33]
It is essential that the one who wants to call people to Islam should have some understanding of that to which he is calling them, but he does not have to know the entire religion, because of the report narrated by al-Bukhaari (3461) from ‘Abd-Allaah ibn ‘Amr (may Allaah be pleased with him), according to which the Prophet (peace and blessings of Allaah be upon him) said “Convey from me, even if it is one verse.” 
Al-Haafiz ibn Hajar (may Allaah have mercy on him) said in Fath al-Baari: He said in the hadeeth, “even if it is one verse” so that everyone who heard him would hasten to convey whatever he heard of the verses, even if it was very little, so that in this manner everything that he (peace and blessings of Allaah be upon him) brought would be conveyed. End quote. 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: If a person understands what he is calling people to, it makes no difference whether he is a great and prominent scholar or a seeker of knowledge who is serious in his pursuit thereof, or a regular person who has certain knowledge of the issue in question. The Messenger (peace and blessings of Allaah be upon him) said: “Convey from me, even if it is one verse,” and he did not stipulate that the daa’iyah (caller) should have reached a high level of knowledge, but it is essential that he should have knowledge of that to which he is calling people. But calling out of ignorance or calling based on emotion is not permissible. End quote. 
Fataawa ‘Ulama’ al-Balad al-Haraam, p. 329. 
Secondly: 
It is permissible for a person to narrate the meaning of a hadeeth according to the majority of scholars, for one who has knowledge of Arabic and is free of the risk of making mistakes or changing the meaning which would lead to changing the ruling. But that changing of the wording is not allowed in the case of words that used in worship such as dhikr and du’aa’ that are narrated in ahaadeeth. 
Shaykh Muhammad ibn ‘Uthaymeen (may Allaah have mercy on him) said: Narrating the meaning of a hadeeth means narrating it in words other than the original wording of the hadeeth. 
This is permissible subject to three conditions: 
1 – That it should come from one who knows its meaning, in the sense that he knows Arabic and he understands the meaning of the report. 
2 – There should be a need for that, such as if the narrator has forgotten the wording of the hadeeth but has memorized the meaning. If he remembers the wording it is not permissible to change it, unless there is a need to explain it to the person being addressed. 
3 – The original wording should not be words that are used in worship, such as the words of dhikr and the like. End quote. 
Majmoo’ Fataawa Ibn ‘Uthaymeen. 
Based on this, there is nothing wrong with narrating the meaning of the hadeeth if you cannot remember the exact words, so long as you do not change the original meaning of the hadeeth. 
Finally, we appreciate your concern to advise your Muslim brothers, and we give you the glad tidings of a great reward with Allaah if your intention is sincere. 
And Allaah knows best.