It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "O people, Hajj has been made obligatory upon you." Sayyiduna al-Aqra' bin Habis (may Allah be pleased with him) said: O Messenger of Allah, every year? The Messenger of Allah (peace and blessings be upon him) remained silent, then said: "No, rather it is obligatory only once; whoever performs Hajj after that, it will be voluntary. Had I said yes, it would have become obligatory upon you, and then you would neither have listened to it nor been able to obey it." This hadith is sahih (authentic) on the condition of Imam Bukhari, but the two Shaykhs did not record it.

It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that Hajj and Umrah are two obligations upon all people except the people of Makkah, for their Umrah is their tawaf itself. (If they wish to perform a separate Umrah,) they should go out to al-Tan'im and then enter (Makkah) from there (in ihram). By Allah, the Messenger of Allah (peace and blessings be upon him) never entered Makkah except in the state of Hajj or Umrah. This hadith is sahih (authentic) on the condition of Imam Muslim, but the two Shaykhs did not record it.

It is narrated from Sayyiduna Zayd bin Thabit (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Indeed, Hajj and Umrah are two obligations; there is no harm to you whichever of them you begin with." And what is correct is that these are the words of Sayyiduna Zayd bin Thabit (may Allah be pleased with him) himself (mawquf).

It is narrated from Sayyiduna Muhammad bin Sirin (may Allah have mercy on him) that Sayyiduna Zayd bin Thabit (may Allah be pleased with him) was asked about performing Umrah before Hajj, and he said: They are like two prayers; it makes no difference to you whichever of them you begin with.

It is narrated from Sayyiduna Nafi' (may Allah have mercy on him) that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) used to say: Upon every one of Allah's creation who has the means, one Hajj and one Umrah are obligatory; then whatever one does after that is good and voluntary. Ibn Jurayj said: It reached me from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that he said: Umrah is obligatory just as Hajj is obligatory, provided one has the means. This chain is sahih (authentic) on the condition of the two Shaykhs.

It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said to her concerning her Umrah: "Indeed, you will have reward in proportion to your hardship and your spending." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it! And it has a sahih supporting narration (shahid) as well:

It is narrated from Sayyidah Aishah (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said to her concerning her Umrah: "The reward of your Umrah is in proportion to your spending."

It is narrated from Sayyiduna Sa'id bin al-Musayyib (may Allah have mercy on him) that Sayyiduna Ali and Sayyiduna Uthman (may Allah be pleased with them both) performed Hajj, and during the journey Sayyiduna Uthman (may Allah be pleased with him) forbade Hajj al-Tamattu' (combining Umrah with Hajj). Sayyiduna Ali (may Allah be pleased with him) was told that he had forbidden tamattu', so Ali (may Allah be pleased with him) said (to his companions): When you see that he has set off, set off too. So Sayyiduna Ali (may Allah be pleased with him) and his companions recited the talbiyah for Umrah, and Uthman (may Allah be pleased with him) did not stop them. Then Ali (may Allah be pleased with him) said: Was I not informed that you forbid tamattu'? He said: Yes. Ali (may Allah be pleased with him) said: Have you not heard that the Messenger of Allah (peace and blessings be upon him) performed tamattu'? He said: Yes indeed. This hadith is sahih (authentic) on the condition of Imam Muslim, but they did not record it.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Here I am for Hajj and Umrah together." This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it!

It is narrated from Sayyiduna Abu Qatadah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) combined Hajj and Umrah together (Hajj al-Qiran) because he (peace and blessings be upon him) knew that he would not perform Hajj again after it. This hadith is sahih (authentic) on the condition of the two Shaykhs (Bukhari and Muslim), but they did not record it.