Mishkat al-Masabih 7 Fasting كتاب الصوم 61

وَعَنِ الْبُخَارِيِّ تَعْلِيقًا قَالَ: كَانَ ابْنُ عُمَرَ يَحْتَجِمُ وَهُوَ صَائِمٌ ثُمَّ تَرَكَهُ فَكَانَ يَحْتَجِمُ بِاللَّيْلِ

Bukhari said without a complete isnad that Ibn ‘Umar used to have himself cupped whan he was fasting. Then he abandoned it and had himself cupped at night.