Nadab

Exodus 24:1, 9
Then the LORD said to Moses, "Come up to the LORD--you and Aaron, Nadab and Abihu, and seventy of Israel's elders--and you are to worship at a distance. . . .

died

Leviticus 10:2
So fire came out from the presence of the LORD and devoured them, and they died before the LORD.

Numbers 3:4
Nadab and Abihu, however, died in the presence of the LORD when they offered strange fire before the LORD in the Wilderness of Sinai. And since they had no sons, only Eleazar and Ithamar served as priests during the lifetime of their father Aaron.

Numbers 26:61
but Nadab and Abihu died when they offered unauthorized fire before the LORD.

Eleazar

Exodus 29:9
Wrap the sashes around Aaron and his sons and put headbands on them. The priesthood shall be theirs by a perpetual statute. In this way you are to ordain Aaron and his sons.

Leviticus 10:12
And Moses said to Aaron and his remaining sons, Eleazar and Ithamar, "Take the grain offering that remains from the offerings made by fire to the LORD and eat it without leaven beside the altar, because it is most holy.

Numbers 16:39, 40
So Eleazar the priest took the bronze censers brought by those who had been burned up, and he had them hammered out to overlay the altar, . . .

Numbers 18:7
But only you and your sons shall attend to your priesthood for everything concerning the altar, and for what is inside the veil, and you are to perform that service. I am giving you the work of the priesthood as a gift, but any outsider who comes near the sanctuary must be put to death."