The Messenger of Allah ﷺ said, "There are three matters in which seriousness is serious and jest is also serious: marriage, divorce, and taking back a wife."
حدثنا القعنبي حدثنا عبد العزيز يعني ابن محمد عن عبد الرحمن بن حبيب عن عطاء بن أبي رباح عن ابن ماهك
أن رسول الله ﷺ قال ثلاث جدهن جد وهزلهن جد النكاح والطلاق والرجعة
[Its chain of transmission is hasan] Tirmidhi narrated it in the Book of Divorce and Lian, Chapter on Seriousness and Jest in Divorce, no. 1184, and Ibn Majah, no. 2039, from the hadith of Abdul-Rahman bin Habib, through the same chain. Hakim graded it sahih, 2/198, and Tirmidhi said, "Hasan gharib." The hadith has corroborating narrations, see Talkhis Habir, 3/210.