Three is a number of completeness and divine emphasis in Scripture. What is repeated three times is established and intensified — the seraphim cry holy, holy, holy; a threefold cord is not quickly broken; God's blessing in Numbers 6 comes in three lines. Three often marks something firm, whole, and God-given.
Above all, three is the number of resurrection: on the third day Jesus rose from the dead, as Jonah was three days and nights in the belly of the fish. And Christians confess God himself as three persons — Father, Son, and Holy Spirit — one God in three, named together at Jesus' baptism and in his final commission. Three is stamped on the deepest realities of the faith: the nature of God, and the victory of Easter morning.
The Number Three in Scripture
For as Jonas was three days and three nights in the whale’s belly; so shall the Son of man be three days and three nights in the heart of the earth.