One Reason for (Provision of) Sustenance

In the blessed time of the Noble Prophet (SallAllahu Alayhi wa Sallam), there were two brothers. Of these two brothers, one would come to the blessed court of the Holy Prophet (SallAllahu Alayhi wa Sallam) in order to seek knowledge of Islam. The other brother was labourer.

One day, the other brother who was a labourer, complained about his brother to the Beloved Prophet (SallAllahu Alayhi wa Sallam) that he has placed the entire burden of earning onto me, and he should help me in labour. The Prophet of Rahmah, the Intercessor of Ummah, the Owner of Jannah (SallAllahu Alayhi wa Sallam) replied, "It might be that you are receiving sustenance by virtue of him."

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Jaami' Tirmidhi, Vol. 4, Page 154, Hadith 2352
Ash'at-ul-Lam'aat, Vol. 3, Chapter 3, Page 262