Whose covenant promises was Peter claiming at Pentecost?
Peter was claiming the covenant promises God made to Abraham. He was still on covenant and kingdom ground at Pentecost, not knowing the 2,000-year age of grace would intervene, so he proclaimed the Abrahamic promises as though they would be fulfilled immediately.
Les explains that Peter, unlike Jesus, did not know where to stop when reading prophecy. Jesus stopped in the middle of Isaiah 61 because the rest would not occur for 2,000 years, but Peter could not put a break between verse 29 and 30. Peter was still on covenant and kingdom ground, claiming the covenant promises God made to Abraham. He had no idea there would be a 2,000-year age of grace, so he continued with the whole prophecy as though it would all take place one thing right after another. The Old Testament program, like Psalms 2, showed Christ's coming, rejection, ascension, tribulation, and then the Kingdom, with no hint of a 2,000-year break. Peter and the people did not know this, so Peter quoted the whole portion as continuous.