Allah said:

﴿أَشْهُرٌ مَّعْلُومَـتٌ﴾

(...the well-known months.)

Al-Bukhari said that Ibn `Umar said that these are Shawwal, Dhul-Qa`dah and the first ten days of Dhul-Hijjah. This narration for which Al-Bukhari did not mention the chain of narrators, was collected by a continuous chain of narrators that Ibn Jarir rendered authentic, leading to Ibn `Umar, who said:

﴿الْحَجُّ أَشْهُرٌ مَّعْلُومَـتٌ﴾

(The Hajj (pilgrimage) is (in) the well-known (lunar year) months.) "which are Shawwal, Dhul-Qa`dah and the (first) ten days of Dhul-Hijjah.'' Its chain is Sahih. Al-Hakim also recorded it in his Mustadrak, and he said,"It meets the criteria of the Two Shaykhs."

This statement is also reported from `Umar, `Ali, Ibn Mas`ud, `Abdullah bin Az-Zubayr, Ibn `Abbas, `Ata', Tawus, Mujahid, Ibrahim An-Nakha`i, Imam Ash-Sha`bi, Al-Hasan, Ibn Sirin, Makhul, Qatadah, Ad-Dahhak bin Muzahim, Ar-Rabi` bin Anas and Muqatil bin Hayyan. This opinion was preferred by Ibn Jarir who said, "It is a common practice to call two months and a part of the third month as `months'. This is similar to the Arab's saying, `I visited such and such person this year or this day.' He only visited him during a part of the year and a part of the day. Allah said:

﴿فَمَن تَعَجَّلَ فِى يَوْمَيْنِ فَلاَ إِثْمَ عَلَيْهِ﴾

(But whosoever hastens to leave in two days, there is no sin on him.)

In this case, one will only be hastening for one and a half days.''

Allah then said:

﴿فَمَن فَرَضَ فِيهِنَّ الْحَجَّ﴾

(So whosoever intends (Farada) to perform Hajj therein (by assuming Ihram),) meaning that one's assuming the Ihram requires a Hajj, for the person is required to complete the rituals of Hajj after assuming Ihram. Ibn Jarir said that Al-`Awfi said, "The scholars agree that (Farada) `intends' mentioned in the Ayah means it is a requirement and an obligation.'' `Ali bin Abu Talhah said that Ibn `Abbas said: f

﴿فَمَن فَرَضَ فِيهِنَّ الْحَجَّ﴾

(So whosoever intends to perform Hajj therein (by assuming Ihram), ) refers to those who assume Ihram for Hajj and `Umrah''. `Ata' said, "'Intends', means, assumes the Ihram.'' Similar statements were attributed to Ibrahim, Ad-Dahhak and others.