What is the eternal security verse that provides assurance of salvation for believers?

One of the key verses that provides assurance of salvation for believers is John 10:28-29, where Jesus says, "I give them eternal life, and they shall never perish; no one will snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Fathers hand." This verse emphasizes the eternal security of believers in the hands of Jesus and the Father.