Abdullah bin Abbas says that (Heraclius asked AbuSufyan) “What this man (Prophet Muhammad, ﷺ) asks of you?” AbuSufyan replied, “He tells us to worship God and not to assign any partners to Him in His Almightiness, to give up the creed of our forefathers and what they did. He also asks us to offer prayers, be truthful, take to the life of charity and meet the claims of our relatives.”
(Sahih Bukhari)
The Emperor of Rome, Heraclius was in Palestine when he received an epistle from the Blessed Prophet. Heraclius ordered that if some people from Hijaz were there, they should be brought to him that he might learn more details. AbuSufyan and some of his companions were found and brought before Heraclius, who put to them many questions.
AbuSufyan said the Prophet stressed the monotheism of God and that they should believe in one God whose authority rules supreme on earth and in the heavens. He controls the world above and the world below. He has taken no partners to Himself in the universe nor can anyone by his influence or force become His partner and hence they should bow to Him alone and seek His help alone in all difficulties, love and obey Him alone and the polytheistic order established by their ancestors should be given up. He also called upon them to pray to God and be true in thought and action and take to a life of charity, not to commit any acts which were against humanity.