Verse 13

لَّوْلَا جَآءُو عَلَيْهِ بِأَرْبَعَةِ شُهَدَآءَ فَإِذْ لَمْ يَأْتُوا۟ بِٱلشُّهَدَآءِ فَأُو۟لَـٰٓئِكَ عِندَ ٱللَّهِ هُمُ ٱلْكَـٰذِبُونَ

They should have produced four witnesses. However, if they could not produce four witnesses, then they are liars as far as God is concerned.