The watchman of Ephraim was with my God: but the prophet is a snare of a fowler in all his ways, and hatred in the house of his God.
The watchman of Ephraim was with my God. The spiritual watchman, the true prophets, formerly consulted my God (Jeremiah 31:6; Habakkuk 2:1); but their so-called prophet is a snare, entrapping Israel into idolatry. The Hebrew is more literal: 'Ephraim was a watchman with my God.' God had designed Ephraim or Israel, as a people, to be the watchman or prophet of God, witnessing for Him among the pagan nations; but instead of this, Ephraim was as "a snare of a fowler in all his ways," led by false prophets himself, and so misleading other nations.
Hatred - rather (a cause of) "apostasy" (see Hosea 9:7). (Maurer.) As the Psalmist saith, "I (am all) prayer," so these false prophets were the embodiment of hatred-hatred personified: their whole soul hating all that was good: and this "in the house of their God!" What an aggravation of their sin the scene of its perpetration was! No wonder, on the principle 'like priest, like people,' that the whole nation, too, was full of "great hatred"! (Hosea 9:7.)
In the house of his God - i:e., the state of Ephraim, as in Hosea 8:1, 'the house of the Lord' (Maurer). Or, 'the house of his (false) god,' the calves (Calvin). Yahweh, "my God," seems contrasted with "his God." Calvin's view is therefore preferable.