John Gill Commentary Hebrews 13:6

"So that with good courage we say, The Lord is my helper; I will not fear: What shall man do unto me?" — Hebrews 13:6 (ASV)

So that we may boldly say
Or confidently assert; for nothing is more true than this,

the Lord is my helper ;
he is able to help, and does help, when none else can; he has promised to be the helper of his people; he has laid help for them on Christ, who is mighty; and he has helped him as man, that he might help them; he has set up a throne of grace for them to come to, where they may find help; and experience confirms the truth of this assertion; every believer can set up an Ebenezer, and say, hitherto hath the Lord helped me:

the people of God are of themselves helpless ones; there is no help for them in man; their help is only in the Lord;

who helps them out of the pit of sin and misery; out of the hands of all their enemies; out of all their afflictions, and "out" of all the dangers they are exposed unto by Satan and his temptations, by reason of a body of sin and death, and no account of the world, and the men of it:

he helps them "in" the exercise of grace, and in the discharge of duty; in bearing the cross; in fighting the Lord's battles; and in their journeying through the wilderness:

he helps them "to" temporal blessings, and spiritual ones; to spiritual food and raiment, and to all needful supplies of grace, and, at last, to eternal glory and happiness:

and the help he now affords is quick and present, suitable and seasonable, and is what is sufficient; and is sometimes with, and sometimes without means.

And I will not fear what man shall do unto me .
There is a becoming fear and reverence which is due to men that are our superiors, whether in civil or religious affairs; but men are not to be feared, when opposed to God; not a single man only is not to be feared, but even all men; and not they only, but all that they can do; the utmost of which is to kill the body;

the ground of this fearlessness in believers are the infinite power, grace, and goodness of God. The words seem to be taken out of (Psalms 54:4) (56:4) (118:6) .