Muwaththa' Malik · #244
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ صَفْوَانَ بْنِ سُلَيْمٍ، - قَالَ مَالِكٌ لاَ أَدْرِي أَعَنِ النَّبِيِّ صلى الله عليه وسلم أَمْ لاَ - أَنَّهُ قَالَ " مَنْ تَرَكَ الْجُمُعَةَ ثَلاَثَ مَرَّاتٍ مِنْ غَيْرِ عُذْرٍ وَلاَ عِلَّةٍ طَبَعَ اللَّهُ عَلَى قَلْبِهِ " .
English
Yahya related to me from Malik that Safwan ibn Sulaym said, "If anyone omits jumua three times without reason or illness, Allah will set a seal on his heart." (Malik said, "I don't know if it was from the Messenger of Allah, may Allah bless him and grant him peace, or not)