Assalaamu alaykum, Sir. The answer that you gave to the question is different. I want the exact anwer. My question is: Can a Salafi perform the prayer like Imam Shaafi'i, may Allaah have mercy upon him, performed it (raising the hands or not raising them) behind a follower of the Hanafi Madhhab (School of Thought)? I mean, can we perform the prayer by raising the hands or not raising them, which differs from how they pray, behind a Hanafi?

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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Raising the hands while reciting Takbeerat Al-Ihraam (opening Takbeer) and before and after Rukoo' (bowing) is a recommended act of the Sunnah in prayer. Whoever observes it shall be rewarded for it, and whoever fails to observe it, his prayer is valid but he misses the reward. There is no harm if the one being led in prayer raises his hands before and after Rukoo’ if he is praying behind an imaam who does not observe this act of the Sunnah.

Shaykh Ibn ‘Uthaymeen wrote:

"If the imaam follows the view that the hands are not to be raised before and after Rukoo‘ and upon standing up after the first Tashahhud, while the one praying behind him follows the view that it is recommended, then the latter may raise his hands, because doing so does not entail any delay in following the imaam or preceding him ... The same applies to the case where the imaam sits in the Tawarruk posture (in which one's buttocks are on the ground while the left foot is laid down and the right foot is held upright, and both are held out to the right) in every Tashahhud that is followed by the Salaam, even in the two-Rak‘ah (unit of prayer) prayer and the follower does not think that he should sit in the Tawarruk posture except in the second Tashahhud of the prayer in which two Tashahhuds are prescribed, then in this case he may refrain from sitting in the Tawarruk posture with his imaam in a two-Rak‘ah prayer because this will not lead to him doing something too late after the imaam or early before him." [Summarized]

That a follower of the Shaafi'i Mathhab prays behind a Hanafi imaam is harmless, and his prayer is valid. Shaykhul-Islam Ibn Taymiyyah was asked, "Is it allowable for the followers of the four Schools of Fiqh to pray behind one another? Is the prayer valid? Did anyone of the Salaf say that they should not pray behind one another?" He replied:

"Praise be to Allah, yes. It is permissible and the prayer is valid. This was the practice of the Companions, the Taabi‘een (the first generation that came after the Companions), and the four Imaams; they used to pray behind each other although they differed in some matters, such as the ones mentioned and others. None of the Salaf said that they should not pray behind one another. Whoever rejects this would be considered committing a religious innovation because his opinion goes against the Quran, the Sunnah, and the consensus of the Salaf of the Ummah and its Imaams..."

Allah knows best.