Narrated Asma:That she conceived `Abdullah bin Az-Zubair. She added, "I migrated to Medina while I was at full term of pregnancy and alighted at Quba where I gave birth to him. Then I brought him to the Prophet (ﷺ) and put him in his lap. The Prophet (ﷺ) asked for a date, chewed it, and put some of its juice in the child's mouth. So, the first thing that entered the child's stomach was the saliva of Allah's Messenger (ﷺ). Then the Prophet rubbed the child's palate with a date and invoked for Allah's Blessings on him, and he was the first child born amongst the Emigrants in the Islamic Land (i.e. Medina)

English translation · Sahih al-Bukhari