Is it permissible to substitute the Istikhara prayer with randomly opening the Mus'haf and interpreting the verses to find a sign that influences decision-making, as in the example of someone seeking a divorce whose mother understands from the story of Musa (peace be upon him) that she should return to her husband?

The Istikhara prayer is a firmly established Sunnah (prophetic tradition) that cannot be replaced by seeking omens (fa'l) from the Qur'an. Seeking omens in this manner is considered forbidden by a group of scholars because it falls under the category of divining by arrows (istiqsam bil-azlam). Al-Qarafi mentioned that Al-Tartushi said that seeking omens from the Qur'an or anything else is forbidden because it is a form of divining by arrows. This is because the one seeking the omen believes that if the outcome is good, they will follow it, and if it is bad, they will avoid it, which is precisely the forbidden divining by arrows.

Al-Nafrawi stated that a good omen (al-fa'l al-hasan) is something that brings comfort to the heart, like a pleasant word heard unintentionally. However, intentionally seeking to hear an omen to act upon it, whether good or bad, is not permissible because it is a form of forbidden divining by arrows. Extracting an omen from the Qur'an is considered a type of divining by arrows.

Shaykh al-Islam Ibn Taymiyyah clarified that seeking omens from the Qur'an has not been transmitted from the Salaf (early Muslims), and later scholars have differed on it. He emphasized that the omen that the Prophet (peace be upon him) loved was hearing a good word after putting one's trust in Allah, not an omen that is relied upon for decision-making. Furthermore, pessimistic omens (at-tīrah) are forbidden, and it was the people of Jahiliyyah (pre-Islamic ignorance) who used to divine by arrows.

In summary, seeking an omen from the Qur'an—meaning opening it and looking at what appears, then basing one's actions on that—is forbidden and is a form of divining by arrows. This is different from a good omen that comes after a person has already started an action, and they hear a pleasant word unintentionally or without searching for it. In marital problems, one should look into their causes and ways to resolve them through legitimate means, such as advice and appointing two arbitrators.