God told Moses to say to Pharaoh, "'Thus says the Lord, 'Let My people go, that they may serve Me''" (Ex 8:1). Then "the frogs came up and covered the land of Egypt" (:6). Next Pharoah said to Moses, 'Entreat the Lord that He remove the frogs'" (:8) and Moses asked "'when shall I entreat for you?'" (:9). The verb used is a synonym for petitioning in a supplicating way. Regarding the plague of the flies, Pharaoh asked Moses to "'Make supplication for me'" (:28) which uses an equivalent word. Moses responded, "I shall make supplication to the Lord'" (:29) and "the Lord did as Moses asked" (:31). Communication was successful. For other plagues, Pharaoh again requested supplication but then hardened his heart afterwards. Both parties were familiar with entreaties, petitions and supplications. However, Pharoah told Moses, "'I have sinned this time; the Lord is the righteous one'" (Ex 9:27). Then he asked for him to "'make supplication to the Lord'" (:28). But Moses replied, "'as for you and your servants, I know that you do not yet fear the Lord God'" (:30).
You might say that the common concept of praying is asking God to solve a problem. Jesus instructed, "'Go into your inner room, close your door and pray to your Father . . . who sees what is done in secret'" (Mt 6:6). Hannah "greatly distressed, prayed to the Lord and wept bitterly" (1Sa 1:10). "She was speaking in her heart, only her lips were moving, but her voice was not heard" (:13). Then Eli answered, "'Go in peace; and may the God of Israel grant your petition that you have asked of Him'" (:17). "The prayer offered in faith will restore the one who is sick, and the Lord will raise him up" (Ja 5:15). Job asked, "'Oh that my request might come to pass, and that God would grant my longing!'" (Job 6:8). God told Hezekiah, "'I have heard your prayer, I have seen your tears; behold I will heal you'" (2Ki 20:5). Elijah was present when a child died. He appealed, "'O Lord my God, I pray You, let this child's life return to him'" (1Ki 17:21). "The Lord heard the voice of Elijah, and the life of the child returned to him and he revived" (:22). God told Abimelech in a dream, "'Restore the man's wife . . . and he will pray for you and you will live'" (Ge 20:7). "Abraham prayed to God, and God healed Abimelech and his wife and his maids, so that they bore children" (:17).