مِشْكَاةُ الْمَصَابِيحِ
Mishkat al-Masabih 331
Purification
Circumstances which make ablution necessary - Section 3
وَعَن ابْن مَسْعُود كَانَ يَقُولُ: مِنْ قُبْلَةِ الرَّجُلِ امْرَأَتَهُ الْوُضُوءُ. رَوَاهُ مَالك
Ibn Mas'ud used to say, “Ablution is necessary when a man kisses his wife.” Malik transmitted it.
Mishkat al-Masabih, 331صَحِيح (الألباني)