In that day. In the day of deliverance and restoration. Though thou wast angry; literally, because thou wast angry. Kay understands an actual hank-fullness for the severe discipline, which had checked them, and not allowed them to glide on smoothly to ruin.
But perhaps the idiom is rather that of the passage, "Father, I thank thee that thou hast hid these things from the wise and prudent, and hast revealed them unto babes" (Matthew 11:25), where it is only the last clause that expresses the true object of the thanksgiving.
Comfortedst; rather, hast comforted, since the effect continued.