Exodus 9:15

“For now will I stretch out my hand, that I may smite thee and thy people with pestilence, etc.] Which yet we never find was done; for though this by many is referred to the slaying of the firstborn, yet it is not certain that this was done by the pestilence: besides, Pharaoh was not then smitten, nor his people, only their firstborn; wherefore these words are to be rendered, not in the future, but in the imperfect or preterpluperfect tense, thus; “for when now I stretched out my hand, or if now I had stretched out my hand to smite thee and thy people with pestilence” f246; that is, at the time when he smote the cattle with the murrain or pestilence, when he could as well have smote him and…”

“With the plague of hail begins the last series of plagues, which differ from the former both in their severity and their effects. Each produced a temporary, but real, change in Pharaoh’s feelings. Exodus 9:14 All my plagues - This applies to all the plagues which follow; the effect of each was foreseen and foretold. The words “at this time” point to a rapid and continuous succession of blows. The plagues which precede appear to have been spread over a considerable time; the first message of Moses was delivered after the early harvest of the year before, when the Israelites could gather stubble, i. e. in May and April: the second mission, when the plagues began, was probably toward the end of…”

“stretch: Exo 9:3, Exo 9:6, Exo 9:16, Exo 3:20 that: Exo 11:4-6, Exo 12:29, Exo 12:30 cut off: Exo 14:28; Kg1 13:34; Pro 2:22 Exodus 9:16”