And my tongue shall speak of thy righteousness - That is, I will praise thee as a righteous God.
And of thy praise - Of that which is a ground or reason for praise. I will speak continually of that in God and in his doings which make it proper that he should be praised.
All the day long - Continually; constantly. Every new proof of the kindness of God to him would lead to new acts of praise; and his life, as ours should be, would be a continual expression of thanksgiving.