When the Holy Prophet (peace be on him) proclaimed his apostlehood, the reaction among the Quraish was violent. Umar, a young man of strong convictions, held the new faith to be a sacrilege of the idols of Katbah. Young, well-built, and fiery-tempered as he was, Umar was in tile forefront in opposition to Islam.
Some accounts have come down to us showing Umar's attitude to Islam in the days before his conversion. Umar has related that in the days of ignorance he was one day standing by an idol with a number of Quraish when an Arab sacrificed a calf. From the belly of the calf the following cry was heard:
"O blood red one,
The deed is done.
A man will cry
Besides God, none."
This corroborated what the Holy Prophet (peace be on him) said. Umar, however, dismissed the cry as sheer hallucination.
It is on record that along with some Arabs Umar went to a soothsayer, and asked him to look into the matter of Muhammad (peace be on him) who had proclaimed a new faith. The soothsayer looked to the beaven for a long time. Then he leapt and said:
"O men, God has honoured and chosen Muhammad,
Purified his heart and bowels.
His stay, among you,
O men will be short."
Umar cursed the soothsayer and returned home very cross and upset.
Lubna, a maid servant of Umar, accepted Islam. When Umar came to know of her conversion, he beat her violently and asked her to retract. She said that he might kill her, but she would not leave Islam. Thereafter it became the wont of Umar that he would beat her every day and would stop beating till he himself felt exhausted. In spite of that, the slave girl remained steadfast.
Umm Abdullah bint Khatamah, a lady related to Umar, also accepted Islam. Umar was very furious at her conversion. As she along with her husband Amar bin Rabiah and other early converts decided to migrate to Abyssinia, Umar felt moved. He visited her and said, "Umm Abdullah are you going?" She said, By God, you have made our living in Mecca very difficult. There is no option with us but to migrate elsewhere." Inadvertently Umar said, 'Umm Abdullah, may God protect you; go in peace." At that time Umm Abdullah felt that in spite of Umar's opposition to Islam, he would one day accept the new faith.
We have it on the authority of Umar himself that one day he came across the Holy Prophet in the Ka'bah. The Holy Prophet was reciting verses from the Holy Quran and as Umar listened to these verses he felt that it was the work of some poet. Then the Holy Prophet recited, "This is the revealed word of God; it's not the work of any poet. Yet you people do not believe". Thereupon Umar felt that if this was not the work of any poet it would be the work of a soothsayer. Thereupon the Holy Prophet recited the verses, "And this is not the word of any soothsayer; it is divine word communicated through Gabriel." Hearing these verses Umar stood transfixed for some time. In his heart of hearts he thought that perhaps truth lay with Muhammad (peace be on him).
Umar, however, dismissed these feelings and soon he was his former self very hostile to Islam. He went to the Quraish and participated in their counsels. They felt concerned that the venom of the new faith was spreading and the only remedy was that Muhammad (peace be on him) should be killed. All present at the meeting agreed that Muhammad (peace be on him) should be killed. Then the meeting invited volunteers who would kill the Prophet. Umar volunteered to kill the Prophet, and vindicate the faith of their forefathers.