سورة Al-Baqarah ( The Cow ) - الآية 273

Those who are engaged so much in the cause of Allah that they cannot move about in the land to earn their livelihood and are, therefore, in straitened circumstances, specially deserve help. An ignorant person would suppose them to be well off because of their self-respect; you can know their real condition from their faces, for they are not the ones who would beg of people with importunity. And Allah will surely know whatever you will spend on them.