Hadith 3421

He reported God’s Messenger as stating that if anyone says, “I am free from Islam,” that is just as he has said if he is lying, but if he is speaking the truth he will not return safely to Islam. Abu Dawud, Nasa’i and Ibn Majah transmitted it.

وَعَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: " مَنْ قَالَ: إِنِّي بَرِيءٌ مِنَ الْإِسْلَامِ فَإِنْ كَانَ كَاذِبًا فَهُوَ كَمَا قَالَ وَإِنْ كَانَ صَادِقًا فَلَنْ يَرْجِعَ إِلَى الْإِسْلَامِ سَالِمًا ". رَوَاهُ أَبُو دَاوُدَ وَالنَّسَائِيُّ وَابْنُ مَاجَهْ

Reference: 5634210
In-book reference: Book 15, Hadith 3421
Hadith 3421 - Oaths and Vows - Mishkat al-Masabih - Sunnah.com