It is narrated from Hazrat Muhajir Qunfudh (may Allah be pleased with him) that he greeted the Holy Prophet (peace and blessings be upon him). The Holy Prophet (peace and blessings be upon him) was performing ablution at that time, so he did not reply. When he had completed the ablution, he replied to his greeting and said: "Nothing prevented me from replying to you except that I did not consider it appropriate to mention the name of Allah while not in a state of ablution." The narrator says that on the basis of this hadith, Khawaja Hasan Basri (may Allah have mercy on him) did not consider it good to recite the Qur'an or remember Allah without ablution.