Jer. 38.10 Then the king commanded Ebed-melech the Ethiopian, “Take thirty men with you from here, and lift Jeremiah the prophet out of the cistern before he dies.
“Let us be courageous when it is necessary, though we have little hope of a favorable outcome.
“…those who think too much about a difficult task often talk themselves into inactivity. They think, ‘What effect can you possibly have? You are only one person, and your enemies are many…such tumult will be raised that you will perish in it.’
“Rest not in [your] own confidence but in God’s favor.
“Let us remember Ebed-melech and hope beyond hope when God requires us to do something. When faith and duty demand anything from us, we must close our eyes to all obstacles and go forward in our work, for all events are in God’s hands alone, and they will happen as he pleases.
“Our duty is to proceed, even if we think our labors may be in vain and will not bear fruit. Ebed-melech happily succeeds in rescuing the prophet because he acts as a pious and upright man in obeying God.
“God will also extend his hand to us, whatever difficulties we encounter, for we shall overcome them by his power and help.”
(John Calvin, quoted in 365 Days With Calvin)