As is the fat taken away from the peace offering, so was David chosen out of the children of Israel.
All Commentaries on Wisdom of Sirach 47:2 Go To Wisdom of Sirach 47
Rabanus Maurus
AD 856
When it says that Nathan, like the fat of salvation, was separated from the meat, it indicates that he was full of the grace of the Holy Spirit and that his conduct and his life were far from and foreign to those of carnal and sinful people.
