[And their prayer at the House was nothing but whistling and clapping]. Al-Hasan said: The whistling is the blowing of breath, and the clapping is the striking of hands together; he says: They used to do that instead of prayer.

Mujahid said: They used to do it to confuse the Prophet (peace and blessings of Allah be upon him) in his prayer.

[So taste the punishment] meaning: the killing by the sword before the punishment of the Hereafter [for what you used to disbelieve].

Surat al-Anfal from verse (36) to verse (40).