Musnad Ahmad Hadith 26938

It is narrated from Asma that she was expecting the birth of Abdullah bin Zubair in Makkah Mukarramah. She says that when I left Makkah Mukarramah, I was full-term. When I reached Madinah Munawwarah and stayed in Quba, I gave birth to Abdullah there. Then I took him to the service of the Prophet (peace be upon him) and placed him in his lap. The Prophet (peace be upon him) called for a date, chewed it, and put his saliva into the child's mouth. Thus, the very first thing that entered his stomach was the saliva of the Prophet (peace be upon him). Then the Prophet (peace be upon him) gave him tahneek with the date and prayed for blessings for him. And he was the first child born to the Muslims in Madinah Munawwarah.