Short answer
Tahnik is softening a date and rubbing a little of it on a newborn's palate. It is sunnah: the Prophet ﷺ did it for babies brought to him. It is mustahabb (recommended) in the Hanafi school, and the four schools agree that it is recommended.
Tahnik is mustahabb. It is best done soon after birth by a righteous person, and it is not obligatory.
The four schools agree on this.
Explanation
Abu Musa al-Ash'ari said that when his son was born he took him to the Prophet ﷺ, who named him Ibrahim, did tahnik with a date and made dua for blessing for him. The Companions brought their newborns to him for this, and the scholars of the four schools agree that it is a recommended sunnah.
How to do it:
- Take a soft date and chew it, or mash it with a little water until it is a smooth paste.
- With a clean finger, rub a very small amount on the upper palate of the baby's mouth, moving the finger gently from side to side.
- Make dua for the baby.
If no date is available, scholars mention something sweet instead. Do not use honey: doctors advise against any honey for babies under one year. For a premature or unwell baby, follow medical advice first. A tiny smear of date paste is enough; the sunnah is the act, not the amount.
The scholars prefer that a pious person does tahnik, hoping for blessing, but a parent or grandparent can do it. It is usually done in the first hours or days, together with the adhan in the ear. Naming can be on the first day, as in this hadith, or on the seventh day with the aqiqah.
The evidence
Sahih al-Bukhari 5467
Sahih... فسماه إبراهيم فحنكه بتمرة ...
"A boy was born to me, so I brought him to the Prophet. He named him Ibrahim and did tahnik for him with a date."
Shows the Prophet doing tahnik and naming the child on the day of birth.
Where the ruling is recorded
- Fath al-Bari (Ibn Hajar), Kitab al-Aqiqah, chapter on naming the newborn and tahnik. Explains the practice and its wisdom.
- al-Minhaj Sharh Sahih Muslim (al-Nawawi), Kitab al-Adab, chapter on tahnik of the newborn. Reports that the scholars agree tahnik with a date is recommended.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.