'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].

وعن عبد الله بن جعفر رضي الله عنهما أن النبي ﷺ أمهل آل جعفر رضي الله عنه ثلاثًا، ثم أتاهم فقال: "لا تبكوا على أخي بعد اليوم". ثم قال: "ادعوا لي بني أخي" فجيء بنا كأننا أفرخ فقال: "ادعوا لي الحلاق" فأمره، فحلق رءوسنا". رواه أبو داود بإسناد صحيح على شرط البخاري ومسلم.