Do you think you can tell the hour when a man goes out and no evil befall him or can warn of the time at which if one goes out harm will accrue? Whoever testifies to this falsifies the Qur'an and becomes unmindful of Allah in achieving his desired objective and in warding off the undesirable. You cherish saying this so that he who acts on what you say should praise you rather than Allah because according to your misconception you have guided him about the hour in which he would secure benefit and avoid harm.

Then Amir al-mu'minin advanced towards the people and said:

O' People! Beware of learning the science of stars except that with which guidance is sought on land or sea, because it leads to divining and an astrologer is a diviner, while the diviner is like the sorcerer, the sorcerer is like the unbeliever and the unbeliever would be in Hell. Get forward in the name of Allah.

(1). When Amir al-mu'minin decided to march towards Nahrawan to suppress the rising of the Kharijites, `Afif ibn Qays al-Kindi said to him, "This hour is not good. If you set out at this time. then instead of victory and success you will face defeat and vanquishment." But Amir al-mu'minin paid no heed to his view and ordered the army to march that very moment. In the result the Kharijites suffered such a clear defeat that out of their nine thousand combatants only nine individuals saved their lives by running away while the rest were killed.

Amir al-mu'minin has argued about astrology being wrong or incorrect in three ways, firstly, that if the view of an astrologer is accepted as correct it would mean falsification of the Qur'an, because an astrologer claims to ascertain hidden things of the future by seeing the stars while the Qur'an says:

Say: "None (either) in the heavens or in the earth knoweth the unseen save Allah... " (27:65)

Secondly that under his misconception the astrologer believes that he can know his benefit or harm through knowing the future. In that case he would be regardless of turning to Allah and seeking His help, while this indifference towards Allah and self-reliance is a sort of heresy and atheism, which puts an end to his hope in Allah. Thirdly, that if he succeeds in any objective, he would regard this success to be the result of his knowledge of astrology, as a result of which he would praise himself rather than Allah, and will expect that whomever he guides in this manner he too should be grateful to him rather than to Allah . These points do not apply to astrology to the extent it may be believed that the astrological findings are in the nature of effect of medicines which are subject to alteration at the will of Allah. The competence achieved by most of our religious scholars in astrology is correct in this very ground that they did not regard its findings as final.