Al-Ahzab 33:5

OdAAoohum li-aba-ihim huwa aqsatuAAinda Allahi fa-in lam taAAlamoo abaahumfa-ikhwanukum fee addeeni wamawaleekumwalaysa AAalaykum junahun feema akhta/tumbihi walakin ma taAAammadat quloobukum wakanaAllahu ghafooran raheema

Call them by [the names of] their fathers; it is more just in the sight of Allāh. 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 Allāh Forgiving and Merciful.

Call them by (the name of) their (real) fathers; It is more equitable in the sight of Allah. And if you do not know their fathers, then they are your brothers in faith and your friends. There is no sin on you in the mistake you make, but in that which you do with intention of your heart; and Allah is Most-Forgiving, Very-Merciful.