5. Speak unto all--The question had been asked in the name of the people in general by Sherezer and Regemmelech. The self-imposed fast they were tired of, not having observed it in the spirit of true religion.
      seventh month--This fast was in memory of the murder of Gedaliah and those with him at Mizpah, issuing in the dispersion of the Jews (2Ki 25:25, 26; Jer 41:1-3).
      did ye . . . fast unto me?--No; it was to gratify yourselves in hypocritical will-worship. If it had been "unto Me," ye would have "separated yourselves" not only from food, but from your sins (Isa 58:3-7). They falsely made the fast an end intrinsically meritorious in itself, not a means towards God's glory in their sanctification. The true principle of piety, reference to God, was wanting: hence the emphatic repetition of "unto Me." Before settling questions as to the outward forms of piety (however proper, as in this case), the great question was as to piety itself; that being once settled, all their outward observances become sanctified, being "unto the Lord" (Ro 14:6).

JFB.