It wasnarrated from Anas bin Malik that the Prophet (ﷺ) said:
"There isnothing standing between a person and Shirk (polytheism)exceptleaving the prayer, so if he leaves it he has committed Shirk." (JA)
English reference (JA): Vol. 1, Book 5, Hadith 1080 (JA)
Arabic reference (JA): Book 5, Hadith 1133 (JA)