The Prophet ﷺ said: There are three things which, whether undertaken seriously or in jest, are treated as serious: Marriage, divorce and taking back a wife (after a divorce which is not final)  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ ثَلاَثٌ جِدُّهُنَّ جِدٌّ وَهَزْلُهُنَّ جِدٌّ النِّكَاحُ وَالطَّلاَقُ وَالرَّجْعَةُ