Hassan ibn Thabit was one of Muhammad's followers and, perhaps, the only poet to be a companion. Duncan Black Macdonald writes:
Further, the story runs that Muhammad used to set up for him a pulpit in the mosque and stand by in evident enjoyment, while Hassan hurled from it stinging verses against the enemies of Islam. This was one of the few occasions on which Muhammad seems to have tolerated poetry, and his reported comment is significant, "Allah aids Hassan with the Holy Spirit so long as he is defending or boasting of the Apostle of God." But by the Holy Spirit here, you must not understand any conception like that of the third person of the Christian trinity. For Muhammad the phrase referred only to the angel messenger who brought to him his revelations. The theological consequences of the lack of the conception of the Holy Ghost, the Lord and Giver of Life, in Islam were wide, but this is not the place to enter upon them. Here Muhammad simply ascribed to Hassan the same kind of inspiration that he had himself, and that is remarkable enough.
Another point to observe is the close parallel between the terms used in the story of Hassan's initiation and that of the first revelation to Muhammad. Just as Hassan was thrown down by the female spirit and had verses pressed out of him, so the first utterances of prophecy were pressed from Muhammad by the angel Gabriel. And the resemblances go still farther. The angel Gabriel is spoken of as the companion (qarin) of Muhammad, just as though he were the Jinni accompanying a poet, and the same word nafatha, "blow upon", is used of an enchanter, or a Jinni inspiring a poet and of Gabriel revealing to Muhammad. It was, or course, the nightmare of Muhammad's earlier years - a fear of his own and an accusation of his enemies - that he was simply a poet possessed by a Jinni; it dictated his whole attitude to poets and poetry, and it is very plain how near the fact, the fear and accusation lay. He was in truth a poet of the old Arab type, without skill of verse, and with all his being given to the prophetic side of poetry. Add to this a strange jumble of Jewish and Christian conceptions, and you have the key to Muhammad. (Source: Duncan B. Macdonald, The Attitude of the Semites Toward the Unseen World; Prophecy as a Semitic Phenomenon and Especially Among the Arabs)
According to Sahih al-Bukhari, Volume 1, Book 8, Number 444, Muhammd believed that Hassan was, like him, inspired by the Holy Spirit, and could reply on his behalf:
I asked Abu Huraira "By Allah! Tell me the truth whether you heard the Prophet saying, O Hassan! Reply on behalf of Allah's Apostle. O Allah! Help him with the Holy Spirit." Abu Huraira said, "Yes."
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