Nafi' narrates: Sayyiduna Umar bin Abd al-Aziz used to fix a share of one hundred dirhams for everyone who had not reached puberty, and he would not fix a share for a newborn child until it was weaned. One night he was going around, and he heard a child crying. He said to its mother: Breastfeed him. She said: The Commander of the Faithful does not fix a share for a newborn child until it is weaned, so I have weaned him. Sayyiduna Umar bin Abd al-Aziz said: In this way I would become guilty of killing him! Breastfeed him; the Commander of the Faithful will soon fix a share for him. After that he fixed a share even for such children, so that a child would receive a share as soon as it was born.
This narration has been recorded by Imam al-Tabarani, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الجهاد / 9777