Asma', daughter of Abu Bakr, reported that when she migrated to Allah's Messenger (ﷺ) in Madinah she was in the family way with'Abdullah bin Zubair in her womb.
Related hadith on this topic
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
The call to prayer (adhan) in the ear of the child can be given by any member of the household.
The hardship and insistence that a prominent and righteous person should be called for this task, or that the child should be taken to such a person, is unnecessary.
However, regarding the practice of tahneek (chewing a date and placing it in the infant’s mouth), this inference can be made.
But the person of the Messenger of Allah (sallallahu alayhi wa sallam) was undoubtedly blessed.
As for other righteous individuals of the ummah, one may have optimistic expectations, but it is not a prescribed (sunnah) practice.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 5106