With regard to the topic, Dr. Salah Sultan, President of Islamic American University, Detroit, US, and former professor of fiqh (Islamic Jurisprudence) at Cairo University, Egypt, answers:
“Abu Hurayrah (may Allah be pleased with him) reports that the Prophet (peace and blessings be upon him) says: “The performance of `Umrah is expiation for the sins committed between it and the previous ones. And the reward for Hajj Mabrur (pilgrimage accepted by Allah) is nothing but Paradise.” (Sahih Al-Bukhari, Vol. 3, Book 27, Hadith no. 1)
It is also reported that the Prophet, peace and blessings be upon him says: “Alternate between Hajj and `Umrah, because both rid one of poverty and sins just as the blacksmith’s bellows removes all impurities from metals like iron, gold and silver. The reward for Hajj Mabrur is nothing short of Paradise.” (Sunan At-Tirmidhi, Vol. 2, chapter on the Reward of Hajj and `Umrah; the Hadith is graded as Hasan Sahih (good and authentic) by Sheikh Al-Albaani, may Allah bless his soul, Hadith no. 650)
The previous Hadith shows that `Umrah serves as an expiation for all types of sins, whether major or minor, because the wording of the Hadith is general and thus it encompasses both categories.
However, there are two main conditions for the acceptance of Hajj and `Umrah:
1. To have complete sincerity (Ikhlas) by performing those rituals solely for the sake of Allah the Almighty.
2. To perform both Hajj and `Umrah the same way it is mentioned in the Sunnah of the Prophet (peace and blessings be upon him).
Generally speaking, it is not necessary to perform `Umrah just for seeking forgiveness for sins, but one should resort to Almighty Allah at every time and place. Allah Almighty says: “And when My servants ask you concerning Me, then surely I am very near; I answer the prayer of the suppliant when he calls on Me, so they should answer My call and believe in Me that they may walk in the right way.” (Al-Baqarah: 186)”