The Gravity of Sin

إِذْ تَلَقَّوْنَهُۥ بِأَلْسِنَتِكُمْ وَتَقُولُونَ بِأَفْوَاهِكُم مَّا لَيْسَ لَكُم بِهِۦ عِلْمٌ وَتَحْسَبُونَهُۥ هَيِّنًا وَهُوَ عِندَ ٱللَّهِ عَظِيمٌ

When you received it with your tongues and said with your mouths that of which you had no knowledge and thought it was insignificant while it was, in the sight of Allāh, tremendous.

وَإِذْ قَالَ لُقْمَـٰنُ لِٱبْنِهِۦ وَهُوَ يَعِظُهُۥ يَـٰبُنَىَّ لَا تُشْرِكْ بِٱللَّهِ ۖ إِنَّ ٱلشِّرْكَ لَظُلْمٌ عَظِيمٌ

And [mention, O Muḥammad], when Luqmān said to his son while he was instructing him, "O my son, do not associate [anything] with Allāh. Indeed, association [with Him] is great injustice."