Look unto Abraham…for I called him alone, and blessed him, and increased him. – Isaiah 51:2

Observe that Abraham was but one man.

I bless God that all my hope of salvation hangs upon the divine ministry of the One Man. Is not Christ, as the servant of God, the very pattern of all ministries which are of God? …When the earth was utterly corrupt God conserved the race by a solitary preacher of righteousness, who prepared an ark for the saving of his house. See how one Joseph saved whole nations from famine, and one Moses brought out a race from bondage. Who was there to keep Israel right when Moses fell to sleep but the one man Joshua? What were the prosperous times in the era of the Judges but days when one man was to the front as a leader? When all the rest hid away in dens and caves, some Barak or Gideon, or Jephthah, or Samson came boldly forward and delivered Israel…What was there but one man in the days of David? The Philistines had still triumphed over the land if the one lad had not brought back Goliath’s head, and if the one man had not again and again smitten the uncircumcised in the name of the Lord. Beloved, if we should ever be reduced, as we shall not be, to one man, yet by one man will God preserve His church, and work out His great purposes. I hope we shall never go into our chamber, and shut the door, and cry with Elias, “I only am left, and they seek my life!” No, my brother, there are more faithful men in this world than you. The Lord has yet reserved to Himself His thousands that have not bowed the knee to Baal. We are this day, not one man, but many, and we all desire to live for the glory of God, and for the spread of His gospel. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/1596.cfm