Is the Fatiha legislated in Islam?

Al-Fatihah is the greatest surah in the Quran. However, it has not been authentically reported from the Prophet (peace be upon him) nor from his Companions that it should be recited on occasions such as condolences, marriage contracts, or buying and selling. Therefore, reciting it in these situations is an innovation (bid'ah), because the fundamental principle concerning acts of worship is that they are prescriptive (tawqif), and anything for which there is no evidence is an innovation.