Daniel Whittle shares another account from D.L. Moody:
At one of the prayer-meetings at the Brooklyn tabernacle, Mr. Moody closed by narrating an instance of persevering prayer by a Christian wife for an infidel husband. She resolved to pray for him at noon for eighteen months, and at the expiration of that time, her knocking not having been responded to, she exclaimed, “Lord, I will pray for him, every day, and at all hours, as long as life lasts.”
That day the Lord heard her knock, and gave her the desire of her heart, in the conversion of her husband. When the Lord saw her faith would not give up, he sent the answer immediately.
I say unto you, Though he will not rise and give him, because he is his friend, yet because of his importunity he will rise and give him as many as he needeth.