Acts 8:14-17 - the people of Samaria were baptized in Christ, but did not receive the fullness of the Spirit until they were confirmed by the elders.
Acts 19:5-6 - the people of Ephesus were baptized in Christ, but Paul laid hands on them to seal them with the Holy Spirit. This sealing refers to the sacrament of confirmation.
Eph. 1:13 - Paul writes that the baptized Ephesians were sealed with the promised Holy Spirit, in reference to confirmation.
Eph. 4:30 - Paul says the Ephesians were sealed in the Holy Spirit of God, in reference to the sealing of confirmation.
Heb. 6:2 - Paul gives instruction to the Hebrews about the laying on of hands, in reference to confirmation, not ordination. The early Church laid hands upon the confirmand to administer the sacrament of confirmation.
Heb. 6:2 - this verse also refers to the cycle of life and its relationship to the sacraments - baptism, confirmation, death and judgment - which apply to all people.
John 6:27 - Jesus says the Father has set His seal on Him. As the Father sets His seal on Jesus, so Jesus sets His seal on us on the sacrament of baptism, and later, in the sacrament of confirmation.
Rev. 9:4 - the locusts could not harm those with the seal of God upon their foreheads. See also Rev. 14:1 and 22:4.