Assalaamu Alaykum. Do you have to maintain an intention throughout prayer? Sometimes when I pray I forget what I am reciting (i.e. if I am reciting al Faatihah or another surah). Does that mean I have to repeat my prayer?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

You should know that intention is to resolve to do something. Intention in prayer is that the worshiper resolves to pray Thuhr or ‘Asr for example. That intention should be made along with the Takbeeratul-Ihraam (first Takbeerah) or a little time before it. Ar-Rawdh Al-Murabba’ reads: “One can have intention while reciting Takbeeratul Ihraam so that the intention can be combined to the act of worship. One can also have it (intention) before Takbeeratul Ihraam in a time that is considered by custom as a little time.” [End quote]

If you come to know that, then intention is not done or renewed inside the prayer. So, if you have intention and recited Takbeer, then you have maintained intention and that is enough.

As for what you have stated that you do not know whether you have recited Al-Faatihah or a Surah, then this does not make it necessary for you to renew intention or to repeat the prayer from the beginning. But if you have doubt whether or not you recited Al-Faatihah while you are still in prayer, then recite it and consider that you have not recited it before. That is because Al-Faatihah is a Rukn (pillar of prayer) and whoever doubts leaving a Rukn of the prayer while he is still in it, has to do it. Ibn Qudaamah said in Al-Mughni: “If one has doubts about leaving a Rukn of the prayer while he is still in it, whether he missed it or not? He is like the one who did not perform it, whether he is leading people in prayer or praying alone because the basic principle is that it was not performed.” [End quote]

Finally, reciting a Surah after Al-Faatihah is something recommended, and thus, if one doubts whether or not he did it, then his doubt has no effect and his prayer is valid.

Allah Knows best.