And in the narration of al-Bukhari:

'he should complete (the prayer) then he should say Taslim and then perform the prostration'.

وَفِي رِوَايَةٍ لِلْبُخَارِيِّ : { فَلْيُتِمَّ , ثُمَّ يُسَلِّمْ , ثُمَّ يَسْجُدْ } .‏ [1]‏