The Messenger of Allah ﷺ said, "Between a servant and disbelief lies the abandonment of prayer."
حدثنا أحمد بن حنبل حدثنا وكيع حدثنا سفيان عن أبي الزبير
قال رسول الله ﷺ بين العبد وبين الكفر ترك الصلاة
[Sahih] Recorded by Tirmidhi, in the Book of Faith, Chapter on what has been said about abandoning the prayer, hadith 2620, from the hadith of Waki, transmitted the same way. Muslim also recorded it, hadith 82, from the hadith of Abu Zubayr, transmitted the same way.