Blessings of tzadikkim

 Ruth Rabbah (06:02) One should never keep back from going to an elder to be blessed. Boaz was eighty years of age, and had not been vouchsafed children. But when that righteous woman prayed for him, he was immediately vouchsafed, as it is said, And Naomi said unto her daughter-in-law: Blessed be he of the Lord  . Resh Lakish said: Ruth was forty years of age and had not yet been vouchsafed children as long as she was married to Mahlon. But as soon as that righteous man prayed for her, she was vouchsafed, as it is said, BLESSED BE THOU OF THE LORD, MY DAUGHTER. The Rabbis, however, say: Both of them were vouchsafed children only as a result of the blessings of righteous people