Adam Clarke on Psalms 111:1

I will praise the Lord with my whole heart - If we profess to "sing to the praise and glory of God," the heart, and the whole heart, without division and distraction, must be employed in the work.

In the assembly - בסוד besod, in the secret assembly - the private religious meetings for the communion of saints. And in the congregation, עדה edah, the general assembly - the public congregation. There were such meetings as the former ever since God had a Church on the earth; and to convey general information, there must be public assemblies.