Islam is clear that apostasy from Islam is a crime and the hadith narrated from the Prophet Muhammad (P) serves as the guide for implementation of the capital punishment.
The hadith is as follows.
“It is narrated that the Prophet, salla allahu alayhi wassallam, said: Whoever changes his religion, kill him”
This narrative, or a part of it with some variations, has been reported in Bukhari (narrative no. 2854, 6524 and 6525), Muslim (narrative no. 1733), Muwatta of Imam Malik (narrative no. 1413), Ibn Hibban (narrative no. 4475 and 5606), Abu Dawud (narrative no. 4351 and 4354), Tirmidhi (narrative no. 1458), An-Nisa’i (narrative no. 4059, 4060, 4061, 4062, 4063, 4064, 4065 and 4066), Ibn Majah (narrative no. 2535), Nisa’i’s Sunan al-Kubra (narrative no. 3522, 3523, 3524, 3525, 3526, 3527, 3528 and 3529), Baihaqi (narrative no. 16597, 16598, 16599, 16635, 16636, 16637, 16654, 16658 and 17841), Ahmad ibn Hanbal (narrative no. 1871, 2551, 2552, 2968, 19681 and 22068), Abu Ya`la (narrative no. 2532 and 2533), Humaidi (narrative no. 533), Abd al-Razzaq (narrative no. 9413, 18705 and 18706), Ibn Abi Shaybah (narrative no. 28992, 29006, 32728, 33143 and 36491). The preferred text is reported in Bukhari’s narrative no. 2854.