Quran An-Nisa 4:3
وَإِنۡ خِفۡتُمۡ أَلَّا تُقۡسِطُواْ فِي ٱلۡيَتَٰمَىٰ فَٱنكِحُواْ مَا طَابَ لَكُم مِّنَ ٱلنِّسَآءِ مَثۡنَىٰ وَثُلَٰثَ وَرُبَٰعَۖ فَإِنۡ خِفۡتُمۡ أَلَّا تَعۡدِلُواْ فَوَٰحِدَةً أَوۡ مَا مَلَكَتۡ أَيۡمَٰنُكُمۡۚ ذَٰلِكَ أَدۡنَىٰٓ أَلَّا تَعُولُواْ ٣
Translation
And if you fear that you will not deal justly with the orphan girls, then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hands possess [i.e., slaves]. That is more suitable that you may not incline [to injustice].