Al-Ahzab 33:5

ٱدۡعُوهُمۡ لِأٓبَآئِهِمۡ هُوَ أَقۡسَطُ عِندَ ٱللَّهِۚ فَإِن لَّمۡ تَعۡلَمُوٓاْ ءَابَآءَهُمۡ فَإِخۡوَٰنُكُمۡ فِي ٱلدِّينِ وَمَوَٰلِيكُمۡۚ وَلَيۡسَ عَلَيۡكُمۡ جُنَاحٞ فِيمَآ أَخۡطَأۡتُم بِهِۦ وَلَٰكِن مَّا تَعَمَّدَتۡ قُلُوبُكُمۡۚ وَكَانَ ٱللَّهُ غَفُورٗا رَّحِيمًا 5

Call them by [the names of] their fathers; it is more just in the sight of Allah. But if you do not know their fathers - then they are [still] your brothers in religion and those entrusted to you. And there is no blame upon you for that in which you have erred but [only for] what your hearts intended. And ever is Allah Forgiving and Merciful