What was the old testament feast that celebrated God saving the first-born of Israel the night they left Egypt?

This would be the feast of 'Passover' (Exodus 12:12-27/Hebrews 11:28(Matthew 26:1/John 1:29/1 Corinthians 5:7), which was so named because God's angel 'passed over' the houses of obedient people, who had followed God's command to put blood on the doorposts of their houses. Those who did NOT listen and obey, suffered great loss with the death of their firstborn. This symbolism pointed forward to the death and pouring out of blood of the coming Messiah(God's 'first born'(Colossians 1:15)...where obedience to God's directives and faith in the blood of that sacrifice, would save lives as it had back in Egypt and under the Mosaic Law for centuries afteward.(1 Peter 1:19-21/Matthew 26:27-28 /Ephesians 1:7/Hebrews 9:22/Leviticus 9:1-24).