en_tn/mat/21/21.md

Truly I say to you

"I tell you the truth." This phrase adds emphasis to what Jesus says next.

if you have faith and do not doubt

Jesus expresses the same idea both positively and negatively to emphasize that this faith must be genuine. Alternate translation: "if you truly believe" (See: rc://en/ta/man/translate/figs-doublet)

you will even say to this mountain, 'Be taken up and thrown into the sea,'

You can translate this direct quotation as an indirect quotation. This can also be stated in active form. Alternate translation: "you will even be able to tell this mountain to get up and throw itself into the sea," (See: rc://en/ta/man/translate/figs-quotations and rc://en/ta/man/translate/figs-activepassive)

it will be done

This can be stated in active form. Alternate translation: "it will happen" (See: rc://en/ta/man/translate/figs-activepassive)