What is the difference between Hajj and sitting after Fajr prayer until sunrise, then praying two rak'ahs, as the Messenger, may Allah bless him and grant him peace, informed that whoever does so will have a reward like that of a complete Hajj?

Sitting after Fajr prayer until sunrise and then praying two rak'ahs is mentioned in the Prophet's saying (peace be upon him): "Whoever prays Fajr in congregation, then sits remembering Allah until the sun rises, then prays two rak'ahs, for him is the reward of a Hajj and an Umrah, complete, complete, complete."

The authenticity of this hadith is debated; some scholars have deemed it weak, while others, like Al-Albani and Ibn Baz, have deemed it good (hasan). The apparent meaning of the hadith indicates a great reward, and this is a bounty from Allah.

Ibn Uthaymeen was asked about this hadith and replied that there is some discussion regarding it, but assuming its authenticity, the reward is immeasurable.

The difference between this sitting and Hajj and Umrah is that Hajj involves spending money, physical exertion, and enduring hardships, and it is an obligatory pillar of Islam. This sitting resembles Hajj only in its reward, and it does not mean that whoever performs it is excused from the obligation of Hajj and Umrah. The purpose of this hadith is to encourage the remembrance of Allah and sitting in the mosque until sunrise and performing two rak'ahs.