Heb 13:1-3
"Let brotherly love continue. Do not neglect to show hospitality to strangers, for thereby some have entertained angels unawares. Remember those who are in prison, as though in prison with them, and those who are mistreated, since you also are in the body."
The ethics of Hebrews: brotherly love (philadelphia), hospitality (philoxenia — love of the stranger), solidarity with prisoners and the mistreated. Hospitality can be an encounter with angels — an allusion to Abraham (Gen 18) and Lot (Gen 19).
Heb 13:8
"Jesus Christ is the same yesterday and today and forever."
The most memorable verse of Hebrews. In contrast to leaders who pass away (13:7), Christ is immutable. Autos kai chthes kai semeron ho autos kai eis tous aionas. The immutability of Christ is the foundation of faith: what He was, He is; what He is, He will be. There is no evolution, revision, or obsolescence in Christ.