Praise be to Allah, The Lord of the Worlds.
In fact, reciting Surah Al-Fatihah upon engagement or conclusion of marriage contract is amongst the lawful matters in Sharia. This is because reciting it on these occasions is one of the means by which a Muslim uses for the purpose of asking Allah for guidance, help and blessing. The righteous predecessors used to recite this Surah to invoke Allah to facilitate matters and fulfill needs. It was reported after A`taa` that he said (What means), "If you want something, recite Al-Fatihah and Allah will answer your call."
It was also reported that some of the companions encouraged reciting this Surah in some situations; yet, there is no specific evidence in this regard. It was narrated in (Musannaf Ibn Abi Shaybah, 29602) that A`sma` Bint Abi Baker (May Allah be pleased with them) said, "Whoever recites Surah Al-Fatihah, Surah Al-Ikhlaas, Surah Al-Falaq and Surah Al-Naas after Friday prayer, Allah safeguards him/her till the next Friday."
According to Muslim jurists, it is desirable prior concluding a marriage contract to deliver a sermon, which includes reciting three verses. It is stated in the Shafie book {Moghni Al-Mohtajj, 2/224 }, "It is desirable to deliver a sermon prior concluding the marriage contract. This is because it was reported that Ibn Mas`oud said, "If any of you wanted to deliver a sermon on the occasion of a marriage and the like, he should say: All praise is due and belongs to Allâh. We praise Him, seek His help and forgiveness and repent to Him. We seek refuge with Allâh from the evils of ourselves and from the wickedness of our own deeds. Whomever that Allâh guides, none can mislead him, and whomever He sends astray, none can guide. I bear witness that there is no deity worthy of worship but Allâh alone with no partner, and I bear witness that Muhammad is His slave and Messenger. "O ye who believe! Observe your duty to Allah with right observance, and die not save as those who have surrendered (unto Him)."{Al-Emran, 102}. "O mankind! reverence your Guardian-Lord, who created you from a single person, created, of like nature, His mate, and from them twain scattered (like seeds) countless men and women;- reverence God, through whom ye demand your mutual (rights), and (reverence) the wombs (That bore you): for God ever watches over you." {An-Nisaa`, 1}. "O People of the Scripture! Why disbelieve ye in the revelations of Allah, when ye (yourselves) bear witness (to their truth) ?"{Al-Ahzaab, 70}. This is called the need sermon."
It is worth pointing out that reciting Al-Fatihah at engagement isn`t tantamount to concluding the marriage contract nor laegally binding; thus, the woman isn`t lawful to the suitor and she remains a non-Mahram to him which entails that he has no guardianship over her, he may not interfere in her affairs and he isn`t allowed to have privacy with her until the marriage contract is concluded.
In this situation, Al-Fatihah serves as marriage promise and preliminary acceptance; however, it isn`t a marriage contract because the latter must have the following pillars: specific words of proposal and acceptance, presence of Guardian (Wali) and witnesses. And Allah the Almighty knows best.
