Muwatta Imam Malik Book of Jumu'a, Hadith 22
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 ﷺ or not.")
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ صَفْوَانَ بْنِ سُلَيْمٍ، - قَالَ مَالِكٌ لاَ أَدْرِي أَعَنِ النَّبِيِّ ﷺ أَمْ لاَ - أَنَّهُ قَالَ " مَنْ تَرَكَ الْجُمُعَةَ ثَلاَثَ مَرَّاتٍ مِنْ غَيْرِ عُذْرٍ وَلاَ عِلَّةٍ طَبَعَ اللَّهُ عَلَى قَلْبِهِ " .