Narrated Samurah ibn Jundub:

The Prophet (ﷺ) said: A boy is in pledge for his Aqiqah. Sacrifice is made for him on the seventh day, his head is shaved and is smeared with blood.

When Qatadah was asked about smearing with blood, how that should be done, he said: When you cut the head (i.e. throat) of the animal (meant for Aqiqah), you may take a few hair of it, place them on its veins, and then place them in the middle of the head of the infant, so that the blood flows on the hair (of the infant) like a threat. Then its head may be washed and shaved off.

Abu Dawud said: In narrating the word "is smeared with blood" (yudamma) there is a misunderstanding on the part of Hammam.

Abu Dawud said: Hammam has been opposed in narrating the words "is smeared with blood". This is misunderstanding of Hammam. They narrated he word "he is given a name (yusamma) and Hammam narrated it "is smeared with blood" (yudamma).

Abu Dawud said: This tradition is not followed.