The two links below contain Ralph Erskine’s two sermons on Haggai 2:19, “From this day will I bless thee”, entitled The Commencement of All Saving Blessings:
These can be found in volume 3 of Erskine’s Works, on pages 99 to 123, and 123 to 144, respectively. The six-volume set of Ralph Erskine’s Works is published by Free Presbyterian Publications and is avaiable from the Bookroom.
Links to previously uploaded material can be found at this page.