﴿ ٱدْعُوهُمْ لِءَابَآئِهِمْ هُوَ أَقْسَطُ عِندَ ٱللَّهِ ۚ فَإِن لَّمْ تَعْلَمُوٓا۟ ءَابَآءَهُمْ فَإِخْوَٰنُكُمْ فِى ٱلدِّينِ وَمَوَٰلِيكُمْ ۚ وَلَيْسَ عَلَيْكُمْ جُنَاحٌۭ فِيمَآ أَخْطَأْتُم بِهِۦ وَلَٰكِن مَّا تَعَمَّدَتْ قُلُوبُكُمْ ۚ وَكَانَ ٱللَّهُ غَفُورًۭا رَّحِيمًا ﴾

“[As for your adopted children,] call them by their [real] fathers’ names: this is more equitable in the sight of God; and if you know not who their fathers were, [call them] your brethren in faith and your friends. However, you will incur no sin if you err in this respect: [what really matters is] but what your hearts intend - for God is indeed much-forgiv­ing, a dispenser of grace!”

(Proclaim their real parentage) name them in relation to their real fathers. (That will be more equitable) better, more correct and fairer (in the sight of Allah) in relation to lineage. (And if ye know not their fathers) if you do not know the lineage of their fathers, (then (they are) your brethren in the faith) name them with names showing brotherhood in faith: 'Abdullah, 'Abd al-Rahman, 'Abd al-Rahim and 'Abd al-Raziq, (and your clients) and name them as your clients. (And there is no sin for you in the mistakes that ye make unintentionally) regarding the identification of one's parentage, (but what your hearts purpose (that will be a sin for you)) what is a sin for you is to attribute intentionally someone to other than his real father. (Allah is Forgiving) of what was done in the past, (Merciful) in relation to what will happen in the future. This verse was revealed about Zayd Ibn Harithah who was adopted by the Prophet (pbuh). People used to call him Zayd Ibn Muhammad, but Allah forbade them from calling him so and guided them to what is proper.