Muwatta Imam Malik Book of Burials, Hadith 26

Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to say, "No-one should pray over a dead person unless he is in wudu."
Yahya said that he heard Malik say, "I have not seen any person of knowledge disapproving of praying over either a child born of adultery or its mother."

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَقُولُ لاَ يُصَلِّي الرَّجُلُ عَلَى الْجَنَازَةِ إِلاَّ وَهُوَ طَاهِرٌ . قَالَ يَحْيَى سَمِعْتُ مَالِكًا يَقُولُ لَمْ أَرَ أَحَدًا مِنْ أَهْلِ الْعِلْمِ يَكْرَهُ أَنْ يُصَلَّى عَلَى وَلَدِ الزِّنَا وَأُمِّهِ .