Concealment of sins

وَجَآءَتْ سَيَّارَةٌ فَأَرْسَلُوا۟ وَارِدَهُمْ فَأَدْلَىٰ دَلْوَهُۥ ۖ قَالَ يَـٰبُشْرَىٰ هَـٰذَا غُلَـٰمٌ ۚ وَأَسَرُّوهُ بِضَـٰعَةً ۚ وَٱللَّهُ عَلِيمٌۢ بِمَا يَعْمَلُونَ

And there came a company of travelers; then they sent their water drawer, and he let down his bucket. He said, "Good news! Here is a boy." And they concealed him, [taking him] as merchandise; and Allāh was Knowing of what they did.

أَيَحْسَبُ أَن لَّمْ يَرَهُۥٓ أَحَدٌ

Does he think that no one has seen him?