Prophet Muhammad (s.a.a.w.) lived a life of poverty from the day he was born till the day he died. Whenever, he had anything valuable, be it food, money, gold, or sheep, he preferred to give all away, even when he and his family were in need.

In an agreed upon hadeeth, the Prophet (s.a.a.w.) said, "If I had as much gold as the weight of Uhud, it would not please me to have a single dinar out of it with me after the passage of three days, but I would hold back something for the repayment of a debt. I would distribute it among the slaves of Allah like this and like this and like this.'' And he (PBUH) pointed in front of him, and on his right side and on his left side. We then walked a little further and he (PBUH) said: "The rich would be poor on the Day of  Resurrection, except he who spent like this and like this and like this,". and he pointed as he did the first time. "But such persons are few".

Abu Hurairah (May allah be pleased with him) reported: Messenger of Allah (PBUH) said: "The world is the believer's prison and the infidel's Jannah (heaven)". [Muslim].

`Abdullah bin `Umar (May allah be pleased with them) reported: Messenger of Allah (PBUH) took hold of my shoulders and said, "Be in the world like a stranger or a wayfarer".

`Aishah (May Allah be pleased with her) reported: Messenger of Allah (PBUH) died when my house was void of any edible thing except for a small quantity of barley I had on a shelf and from which I kept eating it for a long time. Then when I measured what was left of it, it soon finished. [Al-Bukhari and Muslim].

The following commentary is taken from the online version of Riyadu-Saleheen (Chapter 55):

During the last days of the Prophet (PBUH) the financial position of the Muslims had largely improved due to the spoils of war and he could have lived a comfortable life if he liked, but he stuck to the same austere life which he had led earlier. In this Hadith, `Aishah (May Allah be pleased with her) has related an account of the extremely austere and pious life of the Prophet (PBUH) although her house was the house of his most beloved wife.

This Hadith also tells us that in spite of his profound love for `Aishah (May Allah be pleased with him), the Prophet (PBUH) did not accord her any preferential treatment. He treated all his wives equally. Thus, this Hadith has a lesson for `Ulama' and their families that they should not look towards worldly riches and the amenities enjoyed by them but keep in view the life of the Prophet (PBUH) and his wives and learn to keep themselves contented with minimum income.

`Abdullah bin Mas`ud (May Allah be pleased with him) reported: Messenger of Allah (PBUH) slept on a straw mat and got up with the marks left by it on his body. Ibn Mas`ud (May Allah be pleased with him) said, "O Messenger of Allah! Would that you make us spread out a soft bedding for you.'' He (PBUH) replied, "What have I to do with the world? I am like a rider who had sat under a tree for its shade, then went away and left it.''

Commentary: Beside mentioning the piety of the Prophet (PBUH), this Hadith tells in a very eloquent manner the reality of this world by means of an example.

487. Abu Hurairah (May Allah be pleased with him) reported: Messenger of Allah (PBUH) said, "The poor will enter Jannah five hundred years before the rich.''

Commentary:  Al-Fuqara' (the poor) means those Fuqara' who are perfect in Faith. Such people will go to Jannah five hundered years before the rich because the latter will have to account for their wealth, from where they had got it and how they had spent it, while the former will not be answerable for any such thing.

488. Ibn `Abbas and `Imran bin Al-Husain (May Allah be pleased with them) reported: The Prophet (PBUH) said, "I looked into Jannah and saw that most of its dwellers are the poor; and I looked into Hell and saw that most of its inmates were women.''
[Al-Bukhari and Muslim].

Commentary:  The Prophet (PBUH) had observed Jannah and Hell either on the eve of Mi`raj (Ascension to heavens), or of Salat-ul-Kusuf (Eclipse prayer) in which he (PBUH) was shown Jannah and Hell. A large majority of Fuqara' will go to Jannah. The rich people do not attach much importance to the requirements of faith and its practice.

The reason women are the majority in Hell is because they are given to taunts and curses and are ungrateful to their husbands. The Hadith urges women to try to overcome these serious defects in order to be saved from the Hell-fire.

489. Usamah bin Zaid (May Allah be pleased with them) reported: The Prophet (PBUH) said, "I stood at the gate of Jannah and saw that most of those who enter it were poor, whereas the rich were held back; but those who were destined to go to Hell were ordered to be sent there (immediately).''
[Al-Bukhari and Muslim].

Note: The above Ahadeeth and commentary are taken from Riyadus-Saleheen, Chapter 55
Excellence of Leading an Ascetic Life, and Virtues of Simple Life