Sahih al-Bukhari 4662
Narrated Abu Bakr:
The Prophet (ﷺ) said, "Time has come back to its original state which it had when Allah created the 
Heavens and the Earth; the year is twelve months, four of which are sacred. Three of them are in 
succession; Dhul-Qa'da, Dhul-Hijja and Al-Muharram, and (the fourth being) Rajab Mudar (named 
after the tribe of Mudar as they used to respect this month) which stands between Jumad (ath-thani) 
and Sha'ban."
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ عَبْدِ الْوَهَّابِ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَيُّوبَ، عَنْ مُحَمَّدٍ، عَنِ ابْنِ أَبِي بَكْرَةَ، عَنْ أَبِي بَكْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏
"‏ إِنَّ الزَّمَانَ قَدِ اسْتَدَارَ كَهَيْئَتِهِ يَوْمَ خَلَقَ اللَّهُ السَّمَوَاتِ وَالأَرْضَ، السَّنَةُ اثْنَا عَشَرَ شَهْرًا مِنْهَا، أَرْبَعَةٌ حُرُمٌ، ثَلاَثٌ مُتَوَالِيَاتٌ، ذُو الْقَعْدَةِ وَذُو الْحِجَّةِ وَالْمُحَرَّمُ وَرَجَبُ مُضَرَ الَّذِي بَيْنَ جُمَادَى وَشَعْبَانَ ‏"‏‏.‏