Riyad as-Salihin 17:130

'Abdullah bin Ja'far (May Allah be pleased with them) said:

The Prophet (ﷺ) gave respite for three days to the family of Ja'far (after his martydom). Then he came and said, "Don't weep for my brother after this day." He said, "Bring all of my nephews to me." We were accordingly brought as if we were chickens. Then he said, "Call for me a barber." He directed him to shave our heads which he did. [Abu Dawud] .