The Messenger (blessings and peace of Allah be upon him) was the least interested of all people in worldly gain
Question

                Was the Prophet (blessings and peace of Allah be upon him) an ascetic and what is the evidence for that from the Qur’an and Sunnah?
Praise be to Allah.
    The Messenger of Allah (blessings and peace of Allah be upon 
    him) was the least interested of all people in worldly gain, and his 
    asceticism was by choice. If he had wanted, Allah would have turned the 
    mountains into gold for him, and Allah, may He be exalted, enabled him to 
    conquer land and allocated to him one fifth of the booty as his due, and 
    half of the farmland of Khaybar became his… Yet he used to give in charity 
    all the wealth that came to him, and he continued to sleep on the ground and 
    not find anything to eat. 

    When some people spoke about the division of booty, the 
    Prophet (blessings and peace of Allah be upon him) said: “I have nothing of 
    this booty except the khums [one-fifth that was allocated to him], and the 
    khums is returned to you.” Narrated by Abu Dawood (2694); classed as saheeh 
    by al-Albaani in Saheeh Abi Dawood. In other words, the Prophet 
    (blessings and peace of Allah be upon him) did not take for himself the one 
    fifth that was his due share of the booty; rather he used to give it in 
    charity to the Muslims. 

    He (blessings and peace of Allah be upon him) used to say in 
    his supplication: “O Allah, make the provision of the family of Muhammad (no 
    more than) sufficient.” Muslim (1055). 

    In other words, he asked Allah, may He be exalted, to grant 
    him provision that was just enough, and he (blessings and peace of Allah be 
    upon him) did not seek any more than that. 

    There follow some of the hadiths which describe the 
    asceticism of the Prophet (blessings and peace of Allah be upon him) and his 
    lack of interest in worldly gain: 

    It was narrated that ‘Aa’ishah (may Allah be pleased with 
    her) said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    never ate his fill of wheat bread for three days in a row, until he passed 
    away. Narrated by al-Bukhaari (5374) and Muslim (2970). 

    She (may Allah have mercy on her) also said: We used to look 
    at the new moon, then the new moon, then the new moon, three new moons in 
    two months, and no fire would be lit in the houses of the Messenger of Allah 
    (blessings and peace of Allah be upon him). She was asked: What did you live 
    on? She said: The two black ones, dates and water, but the Messenger of 
    Allah (blessings and peace of Allah be upon him) had some neighbours from 
    among the Ansaar and they had milch-animals; they would send some of their 
    milk to the Messenger of Allah (blessings and peace of Allah be upon him), 
    and he would give it to us to drink.

    Narrated by al-Bukhaari (2567) and Muslim (2972) 

    It was narrated from her (may Allah be pleased with her) that 
    she said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    died when there was nothing on my shelf that a living being could eat except 
    a handful of barley.

    Narrated by al-Bukhaari (3097) and Muslim (2973). 

    And she (may Allah be pleased with her) said: When the 
    Messenger of Allah (blessings and peace of Allah be upon him) died, he had 
    not eaten his fill of bread and olive oil twice in one day. 
    

    Muslim (2974) 

    It was narrated that an-Nu‘maan ibn Basheer (may Allah be 
    pleased with him) said: ‘Umar mentioned what people had got of worldly gains 
    and he said: I saw the Messenger of Allah (blessings and peace of Allah be 
    upon him) spending the whole day suffering because of hunger, and he could 
    not even find inferior-quality dates with which to fill his stomach.

    Narrated by Muslim (2978) 

    It was narrated from Anas ibn Maalik (may Allah be pleased 
    with him): The Prophet (blessings and peace of Allah be upon him) never ate 
    soft bread or a roasted sheep until he met Allah.

    Narrated by al-Bukhaari (5385). 

    It was narrated that Ibn ‘Abbaas (may Allah be pleased with 
    him) said: The Messenger of Allah (blessings and peace of Allah be upon him) 
    would remain hungry for several nights in a row, and his family would not be 
    able to find any supper, and most of their bread was barley bread.

    Narrated by at-Tirmidhi (2360); classed as hasan by al-Albaani 
    in Saheeh at-Tirmidhi

    It was narrated from Abu Hurayrah (may Allah be pleased with 
    him) that the Messenger of Allah (blessings and peace of Allah be upon him) 
    used to tie a stone to his stomach because of hunger. Narrated by Ibn al-A‘raabi 
    in al-Mu‘jam (21); classed as hasan by al-Albaani in as-Silsilah 
    as-Saheehah (1615) 

    ‘Amr ibn al-Haarith (may Allah be pleased with him) said: The 
    Prophet (blessings and peace of Allah be upon him) left nothing behind 
    except his weapon, his white mule and some land that he left behind as a 
    charity.

    Narrated by al-Bukhaari (3098) 

    It was narrated that ‘Abdullah ibn Mas‘ood (may Allah be 
    pleased with him) said: The Messenger of Allah (blessings and peace of Allah 
    be upon him) slept on a reed mat, and when he got up it had left marks on 
    his side. We said: O Messenger of Allah, why don’t we make a mattress for 
    you? He said: “I have no need of worldly comfort; I am in this world like 
    one who is on a journey, and halted to seek shade beneath a tree, then soon 
    moved on and left it.” 

    Narrated by at-Tirmidhi (2377); classed as saheeh by al-Albaani 
    in Silsilat al-Ahaadeeth as-Saheehah (438) 

    The hadiths that speak of his asceticism and lack of interest 
    in worldly gain are too many to be counted, but what we have quoted here is 
    sufficient. 

    And Allah knows best.