Muwatta Imam Malik Book of Purity, Hadith 67

Yahya related to me from Malik that he had heard that Abdullah ibn Masud used to say, "Wudu is necessary if a man kisses his wife."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَبْدَ اللَّهِ بْنَ مَسْعُودٍ، كَانَ يَقُولُ مِنْ قُبْلَةِ الرَّجُلِ امْرَأَتَهُ الْوُضُوءُ .