We relate in the Ṣaḥīḥs of al-Bukhārī and Muslim that Asmā’ bint Abī Bakr 
narrated: “I conceived ‘Abdullāh ibn az-Zubayr in Makkah. We came to Madīnah and I stopped at Qubā’ and gave birth there. Then I brought him to the Prophet 
, who put him on his lap, called for a date and chewed it, then put it into his mouth. So the first thing that went into [the baby’s] belly was the saliva of the Messenger of Allah . He performed taḥnīk with a date, made du‘ā’ for him and blessed him.” [3].
narrated: “I conceived ‘Abdullāh ibn az-Zubayr in Makkah. We came to Madīnah and I stopped at Qubā’ and gave birth there. Then I brought him to the Prophet , who put him on his lap, called for a date and chewed it, then put it into his mouth. So the first thing that went into [the baby’s] belly was the saliva of the Messenger of Allah . He performed taḥnīk with a date, made du‘ā’ for him and blessed him.” [3].We relate in both Ṣaḥīḥs that Abū Mūsā al-Ash‘arī 
related: “A boy was born to me, and I brought him to the Prophet , who named him Ibrāhīm. He performed taḥnīk for him with a date and prayed for blessings on him.” [4].That is the wording in both al-Bukhārī and Muslim except for the words “And prayed for blessings on him”, which are specific to al-Bukhārī.
related: “A boy was born to me, and I brought him to the Prophet , who named him Ibrāhīm. He performed taḥnīk for him with a date and prayed for blessings on him.” [4].That is the wording in both al-Bukhārī and Muslim except for the words “And prayed for blessings on him”, which are specific to al-Bukhārī.References
[1] Taḥnīk means chewing something sweet until it is almost liquid, and then opening the mouth of the newborn baby and putting it in.
[2] Abū Dāwūd (5106).
[3] Al-Bukhārī (3909) and Muslim (2146).
[4] Al-Bukhārī (6198) and Muslim (2145).