Muwatta Malik 545

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 ‏.‏

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

Reference

Muwatta Malik 545

In-book

Book 16, Hadith 26