secret fasting

"...But particularly, his example and success with regard to one duty, in an especial manner, may be of great use to both ministers and private Christians; I mean the duty of secret fasting. The reader has seen, how much Mr. Brainerd recommends this duty, and how frequently he exercised himself in it; nor can it well have escaped observation, how much he was owned and blessed in it, and of what great benefit it evidently was to his soul. Among all the many days he spent in secret fasting and prayer, that he gives an account of in his diary, there is scarce an instance of one, but what was either attended or soon followed with apparent success, and a remarkable blessing, in special incomes and consolations of God's Spirit; and very often, before the day was ended.--But it must be observed, that when he set about this duty, he did it in good earnest; "stirring up himself to take hold of God," and "continuing instant in prayer," with much of the spirit of Jacob, who said to the angel, "I will not let thee go, except thou bless me."

From The Life of David Brainerd, ed. Norman Pettit, The Works of Jonathan Edwards, Vol. 7, (New Haven: Yale University Press)