New Defender's Study Bible Notes
20:5 the new moon. The first days of the month were apparently being observed as special feast days (e.g., Numbers 10:10), and David was expected to be present in the court on such days.
20:15 from my house for ever. Jonathan realized that David would eventually become king, and he was also aware that victorious kings in that day often slew all the sons of their predecessors in order to thwart their own ambitions to the throne. David later kept his promise to Jonathan (II Samuel 21:7).