in the day. See App-18.
from the iron furnace. Reference to Pentateuch (Deuteronomy 4:20).
Obey. Hear, with Beth (= B). Listen or attend to.
Obey My voice. Reference to Pentateuch (Exodus 15:26). App-92.
them: i.e. "the words" of Jeremiah 11:3.
I will be your God. Reference to Pentateuch (Leviticus 26:3-12).