The fact that his mouth betrayed him and said "hold on", even when he thought that the river will take them under. (Meaning he is also the one who eventually made them swim in the river.)
The fact that he "said to his friend that he will be saved" yet knowing that it's not true just "by looking at his face".
The fact that after knowing that his friend couldn't be saved, his friend still kept telling him that "it's OK".
So, it's just a thought of Guilt that could only be known between him, his friend (who eventually dies) and the river.
Wash him clean for all the false hopes that he (and probably his friend) has made made.
"Wash him clean" for...
So, it's just a thought of Guilt that could only be known between him, his friend (who eventually dies) and the river. Wash him clean for all the false hopes that he (and probably his friend) has made made.