Are There Any Rules of Taking an Agnomen (kunya)?

Answered by Ustadh Tabraze Azam
Question: Assalaamu alaikum wa rahmatullahi wa barakatoh,
How do kunyas (e.g. Abu Muhammad) work in Islam? Is it religious or cultural practice for one to change their kunya if they have a daughter, then later have a son?
Answer: Wa alaikum assalam wa rahmatullahi wa barakatuh,
I pray that this finds you in the best of health and spirits, insha’Allah.
Taking an agnomen (kunya) is permitted. (e.g. Abu Ibrahim)
It is a recommended sunna to use the name of your eldest child for the kunya. Though, it is permitted to take any kunya you wish, even if you do not have any children. There is much leeway in this as long as the chosen name is not undignified or unbefitting in any way.
[Ibn `Allan/Nawawi, al-Futuhat al-Rabbaniyya `ala al-Adhkar al-Nawawiyya; al-Mawsu`ah al-Fiqhiyya al-Kuwaitiyya]
And Allah alone gives success.
wassalam,
Tabraze Azam
Checked & Approved by Faraz Rabbani