Answered by Shaykh Faraz Rabbani
I heard it is sunna to recite tasbihs while standing in the last two rakats. What does this mean? Is this instead of the Fatiha, or with it, or do we have a choice

Walaikum assalam,
In the Hanafi school, it is not necessary (wajib) to recite the Fatiha in the third and fourth rakats of the prayer. Rather, it is a sunna to recite the Fatiha. The sunna is also fulfilled by saying the tasbihs (=saying SubhanAllah) three times.
This has been transmitted, by Ibn Abi Shayba in his Musannaf and others, from Ali, Abd Allah ibn Mas`ud, Ibrahim al-Nakha`I, and others, with sound chains of transmitters. Details may be found in I`la’ al-Sunan.
Abu Ishaq reported from both Ali and Abd Allah [ibn Mas`ud] that they said, “Recite in the first two, and do tasbihs in the last two.” (Musannaf Ibn Abi Shayba) That is, it is permitted to do so.
Note, however, that reciting the Fatiha is superior, even though both are permitted.
Note, too, that this is only in obligatory prayers. In one’s witr, sunnah, and nafl prayers, it is necessary to recite in every rakat.
And Allah alone gives success.
Wassalam,
Faraz.