Supplication (also known as petitioning) is a form of prayer, wherein one party humbly or earnestly asks another party to provide something, either for the party who is doing the supplicating (e.g., "Please spare my life.") or on behalf of someone else (e.g., "Please spare my child's life.").

In Christianity, the prayer of supplication for health by and on behalf of the sick is referenced in early Christian writings in the New Testament, especially James 5:13-16.

One example of supplication is the Catholic ritual of novena (from novem, the Latin word for "nine") wherein one repeatedly asks for the same favor over a period of nine days. This ritual began in Spain during the Middle Ages when a nine-day period of hymns and prayers led up to a Christmas feast, a period which ended with gift giving. A contemporary Christian example of supplication is the practice of the Daily Prayer for Peace by the Community of Christ where a member prays for peace each day at a specified time. Philippians 4:6 says, "Be anxious for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God."