The Quran

ادعوهُم لِآبائِهِم هُوَ أَقسَطُ عِندَ اللَّهِ ۚ فَإِن لَم تَعلَموا آباءَهُم فَإِخوانُكُم فِي الدّينِ وَمَواليكُم ۚ وَلَيسَ عَلَيكُم جُناحٌ فيما أَخطَأتُم بِهِ وَلٰكِن ما تَعَمَّدَت قُلوبُكُم ۚ وَكانَ اللَّهُ غَفورًا رَحيمًا

Muhammad Asad

[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.¹ However, you will incur no sin if you err in this respect:² [what really matters is] but what your hearts intend - for God is indeed much-forgiving, a dispenser of grace!

I.e., "make it clear that your relationship is an adoptive one, and do not create the impression that they are your real children" - thus safeguarding their true identity.
I.e., by making a mistake in the attribution of the child's parentage, or by calling him or her, out of love, "my son" or "my daughter".