Isaiah 48:18

Failure to listen and hear the Lord’s instruction (cf. Isaiah 48:1; Isaiah 48:4; Isaiah 48:8) in the past had limited Israel’s peace (Heb. shalom) and her right conduct (Heb. sedaqa). Things could have been far better if she had only listened and obeyed. She could have experienced a ceaseless, powerful flow of His blessings.

"Every sensitive teacher knows the pain of heart that comes when he pours himself out for students who prove to be unteachable. Israel proved to be like that (cf. Isaiah 48:8); and God expresses his deep concern for them, because they are themselves the losers." [Note: Grogan, p. 281.]