Psalms 89:2

“For I have said, etc.] That is, in his heart he had said, he had thought of it, was assured of it, strongly concluded it, from the Spirit and word of God; he believed it, and therefore he spoke it; having it from the Lord, it was all one as if he had spoke it:”

“For I have said - The Septuagint and the Latin Vulgate render this, “Thou hast said,” which is more in accordance with what the connection seems to demand; but the Hebrew will not admit of this construction. The true meaning seems to be, that the psalmist had said; that is, he had said in his mind; he had firmly believed; he had so received it as a truth that it might be spoken of as firmly settled, or as an indisputable reality. It was in his mind one of the things whose truthfulness did not admit of a doubt. Mercy shall be built up for ever - The mercy referred to; the mercy manifested in the promise made to David. The idea is, that the promise would be fully carried out or verified. It…”

“Establish - As firmly and durably as the heavens themselves. Psalms 89:3”

“Mercy: Psa 36:5, Psa 103:17; Neh 1:5, Neh 9:17, Neh 9:31; Luk 1:50; Eph 1:6, Eph 1:7 faithfulness: Psa 89:5, Psa 89:37, Psa 119:89, Psa 146:6; Num 23:19; Mat 24:35; Heb 6:18 Psalms 89:3”