My small son accompanied me on hajj. Is his hajj valid and does it fulfill the obligation?
Ibn `Abbas (may God be pleased with them both) narrated that the Prophet (peace and blessings be upon him) met some riders at Al-Rawha’. He asked them: “Who are you?” They said, ‘We are Muslims. Who are you?” The Prophet replied, ‘I am the Messenger of God.’ At this, a woman lifted a child and asked, “Is hajj valid for this [child]?” The Prophet replied, “Yes, and you will be rewarded.” [recorded by Muslim].
Your son’s hajj is valid provided you completed its integrals and duties on his behalf. As he will earn the reward of a voluntary hajj, it does not fulfill the obligation because obligatory acts of worship are only mandatory upon a legally accountable person, which a child is not.
And God the Almighty knows best.
Staff of Dar al-Iftaa al-Misriyyah