Exodus 9:29
28 Pray to the Lord, for the mighty thunderings and hail are too much! I will release you and you will stay no longer.” 29 Moses said to him, “When I leave the city I will spread my hands to the Lord, the thunder will cease, and there will be no more hail, so that you may know that the earth belongs to the Lord. 30 But as for you and your servants, I know that you do not yet fear the Lord God.”
Onkelos Exodus 9:29
28 Pray before the Lord that relief may be multiplied before Him, so that there may be upon us no more thunders of malediction like these before the Lord, nor hail; and I will send you away, and will not continue to detain you. 29 And Mosheh said to him, When I shall have gone out of the city, I will spread forth my hands in prayer before the Lord, and the thunders shall cease, and there shall be no more hail, that you may know that the earth is the Lord's. 30 But (as for) thee and thy servants, I know that as yet ye are not humbled before the Lord God.
Notes and References
"... There is no verse in the Pentateuch that explicitly describes a person as praying. Prayer, as we understand it today, evolved and developed over many centuries. Nevertheless, there are seventeen instances in Exodus in which our targumist describes an act with the term 'prayer,' thereby suggesting that he felt the deed should be understood as a prayer. Thus, in verse 9:29, he clarifies the ambiguous phrase 'spread out my hands,' by attaching the phrase 'in prayer' ..."
Drazin, Israel, and Stanley M. Wagner Onkelos on the Torah, Exodus: Understanding the Bible Text (p. 52) Gefen, 2006