'Observed' in the Bible

And God gave Abraham a covenant [a formal agreement to be strictly observed] of [which] circumcision [was the sign]; and so [under these circumstances] Abraham became the father of Isaac, and circumcised him on the eighth day; and Isaac [became the father] of Jacob, and Jacob [became the father] of the twelve patriarchs.

and looking closely at it, I saw all kinds of the four-footed animals of the earth and the wild beasts and the crawling creatures and the birds of the air [both clean and unclean according to the Law],

Now as I was going along and carefully looking at your objects of worship, I came to an altar with this inscription: ‘TO AN UNKNOWN GOD.’ Therefore what you already worship as unknown, this I proclaim to you.