Musannaf Ibn Abi Shaybah 25027 — Dates used for the tahnik

It is narrated from Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) that she came to the Prophet (peace and blessings be upon him) with Ibn al-Zubayr (may Allah be pleased with him), when Sayyidah Asma had given birth to him. The Companions looked for a date until one was found, and then they rubbed his palate with it. So the first thing that entered the belly of Sayyiduna Ibn al-Zubayr (may Allah be pleased with him) was the blessed saliva of the Messenger of Allah (peace and blessings be upon him).