It wasnarrated from Ka'b bin 'Ujrah that the Messenger of Allah(ﷺ)saw a man who had interlocked his fingers during the prayer, sotheMessenger of Allah (ﷺ) separated his fingers. (FR)
English reference (FR): Vol. 1, Book 5, Hadith 967 (FR)
Arabic reference (FR): Book 5, Hadith 1020 (FR)