1 Samuel 20:11

And Jonathan said to David, "Come, let us go out into the field," etc. A marvelous way of speaking, as if he began to speak to God, which yet he completed in speaking to a man; but this was due to the incomparably ardent affection between the young men, mutually commending each other in virtue; this as a sign of faith, always and everywhere to be kept with God as witness; which grammarians call the figure paraprosdociam in Greek, that is, an unexpected outcome. Therefore, Jonathan and David, first secretly in the city, then also going out into the field, make a covenant of the Lord, so that Jonathan would not hide from David anything that his father might think good about him; he would not introduce him to his father unless perhaps converted to piety; but also Jonathan himself, if he lives, would receive mercy from David; if indeed he dies, David would show mercy to his house forever. Because the primitive Church at its beginning was to no small extent judaizing, but soon, going out into the fruitful breadth of Christian liberty, entered into a covenant with the Lord of perpetual love; it was agreed that if any of the Jewish persecutors of Christ wished to recognize goodness and turn to him, their faith and conversion would immediately be made known to his faithful members, that is, to the Church itself, so that they might obtain full salvation by its association, and not cast pearls before swine, not profane its sacraments to the unbelievers, but rather believe that they should be piously received by those who would rejoice to live in peace. And if indeed among the Jews the state and life of the Church would remain intact, they would not be crowned by their own merit as believers, but by the compassion and mercy of their Author. And if, by their scorning, the way of life turned to themselves, nevertheless, to any believing among that people individually until the end of the age, and to all converted remnants together at the end, entrance to mercy would not be denied.