“The Messenger of Allah (ﷺ) said: ‘Between a person and Kufr (disbelief) is abandoning the prayer.’”
Sunan Ibn Majah Book 5, Hadith 276
← Previous Hadith “We went out with the Messenger of Allah (ﷺ) from Al-Madinah to Makkah, during which time we shortened our prayer to two Rak’ah, until we came back.” I asked: “How long did he stay in Makkah?” He said: “Ten (days).”

Sunan Ibn Majah Book 5, Hadith 275 Next Hadith → “The Messenger of Allah (ﷺ) said: ‘The covenant that distinguishes between us and them is prayer; so whoever leaves it, he has committed Kufr.’”

Sunan Ibn Majah Book 5, Hadith 277