What does this verse mean?

[AbooAbdurRahman]

Assalaamu alaykum wa rahmatullaahi wa barakatuhu

Can anyone provide me an explanation of this Ayah and specifically of the parable Allaah uses in His the Most High's statement:

"Muhammad is the Messenger of Allah ; and those with him are forceful against the disbelievers, merciful among themselves. You see them bowing and prostrating [in prayer], seeking bounty from Allah and [His] pleasure. Their mark is on their faces from the trace of prostration. That is their description in the Torah. And their description in the Gospel is as a plant which produces its offshoots and strengthens them so they grow firm and stand upon their stalks, delighting the sowers - so that Allah may enrage by them the disbelievers. Allah has promised those who believe and do righteous deeds among them forgiveness and a great reward."

The highlighted part is what i'm most interested in understanding but I would like to read a detailed explanation of it all. BarakAllaahu feekum.