John Wesley on John 13:23

There was lying in the bosom of Jesus - That is, sitting next to him at table. This phrase only expresses the then customary posture at meals, where the guests all leaned sidewise on couches. And each was said to lie in the bosom of him who was placed next above him. One of the disciples whom Jesus loved - St. John avoids with great care the expressly naming himself. Perhaps our Lord now gave him the first proof of his peculiar love, by disclosing this secret to him.