John Gill Commentary Mark 1:41

"And being moved with compassion, he stretched forth his hand, and touched him, and saith unto him, I will; be thou made clean." — Mark 1:41 (ASV)

And Jesus, moved with compassion
At the sad and deplorable case the poor man was in, being a merciful high priest, and not with a desire of popular applause, and vain glory:

put forth his hand and touched him ;
though the leprosy was spread all over him, and there was no place clean, and touching him was forbidden by the law:

and says to him, I will be you clean; (See Gill on Matthew 8:3).