From the Quran.
إِنَّ عِدَّةَ ٱلشُّهُورِ عِندَ ٱللَّهِ ٱثۡنَا عَشَرَ شَهۡرٗا فِي كِتَٰبِ ٱللَّهِ يَوۡمَ خَلَقَ ٱلسَّمَٰوَٰتِ وَٱلۡأَرۡضَ مِنۡهَآ أَرۡبَعَةٌ حُرُمٞۚ
Verily, the number of months with Allah is twelve months (in a year), so was it ordained by Allah on the Day when He created the heavens and the earth; of them four are Sacred, (i.e. the 1st, the 7th, the 11th and the 12th months of the Islamic calendar).
Quran Surah Al- Tawbah 9: 36.
Hadith: Arabic Text followed by English Translation.
عن أبي بكرة – رضي الله عنه – أن النبي صلى الله عليه وسلم خطب في حجة الوداع وقال في خطبته
إن الزمان قد استدار كهيئة يوم خلق السماوات والأرض السنة اثنا عشر شهرا منها أربعة حرم ثلاث متواليات ذو القَعدة وذو الحجة والمحرم ورجب مضر الذي بين جمادى وشعبان .
رواه البخاري رقم (1741) في الحج باب الخطبة أيام منى ، ورواه مسلم رقم (1679) في القسامة باب تحريم الدماء .
It was reported from Abu Bakrah (may Allaah be pleased with him) that the Prophet SAWS (peace and blessings of Allaah be upon him) gave his Farewell Sermon and said:
Time has completed its cycle and is as it was on the Day when Allaah created the heavens and the earth. The year is twelve months, of which four are sacred, three consecutive months – Dhoo’l-Qa’dah, Dhoo’l-Hijjah and Muharram – and the Rajab of Mudar which comes between Jumaada and Sha’baan.
Reported by al-Bukhaari, no. 1741, in [Kitaab] al-Hajj, al-Khutbah Ayaam Mina; and by Muslim, no. 1679, in [Kitaab] al-Qisaamah, Baab Tahreem al-Dimaa’
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