‘Ammar (RA) said, “Whoever possesses three (characteristics) has attained eemaan: gives other people what is due to them, spreads the greeting (of salaam) to everyone, and spends [in the way of Allah] even when he is poor.”‘Abdullah ibn ‘Amr narrated that a man asked the Messenger of Allah صلى الله عليه و سلم, “What aspect of Islam is best?” He replied, “To feed people and to greet (with salaam) those you know and those you do not know.” [Sahih Bukhari, Chapter 2- The Book of Faith (Iman), Hadith 18]
Imam Ibn Hajar’s Explanation in 'Fath Al Bari':
His saying, “Propagating the greetings (salaam) is part of Islam.”
Propagating the greeting includes doing so openly or secretly, which also coincides with his صلى الله عليه و سلم saying, “to those you know and those you don’t know.”
His saying, “and spends [in the way of Allah] even when he is poor.”
In the narration, the word ‘Al-Iqtaar’ (الإقتار) means when he has little. Abu Al-Zanad Ibn Siraaj and others said that whoever combines between these three characteristics attains complete eemaan because a person who fulfils the rights (of people) will not fail to fulfill the rights of his lord, which are obligatory upon him, nor will he indulge in what has been prohibited. Such a person has achieved the pillars of eemaan.
Spreading the greetings (of salaam) is a part of good character and humbleness, and it brings about unity and love.
Giving charity in times of hardship proves a high level of generosity. The one who gives (charity) even though he himself is in need, is certain to give even more generously when his wealth increases. Giving charity is broad; spending on one’s family in ways that are obligatory and/or preferred, and spending for one’s guest and visitors are part of charity. Giving in times of hardship proves trust in Allah and detachment from the worldly life. The wisdom and combination of short expressions carrying extensive and complete meaning are proof of the authenticity of this narration.