John 15:4-6

Remain united to me, and I will remain united to you. As a branch cannot bear fruit by itself, unless it remains united to the vine; no more can you, unless you remain united to me.

Acts 11:23

On coming there he saw to his great joy these tokens of the loving-kindness of God, and encouraged them all to make up their minds to be faithful to the Lord--

Acts 27:31

When Paul said to the Roman Officer and his men: "Unless the sailors remain on board, you cannot be saved."

Hebrews 3:14

For we now all share in the Christ, if indeed we retain, unshaken to the end, the confidence that we had at the first.

Hebrews 6:4-8

For if those who were once for all brought into the Light, and learned to appreciate the gift from Heaven, and came to share in the Holy Spirit,

Hebrews 9:11-12

But, when Christ came, he appeared as High Priest of that Better System which was established; and he entered through that nobler and more perfect 'Tabernacle,' not made by human hands--that is to say, not a part of this present creation.

Hebrews 9:15-17

And that is why he is the intermediary of a new Covenant; in order that, as a death has taken place to effect a deliverance from the offenses committed under the first Covenant, those who have received the Call may obtain the eternal inheritance promised to them.

Hebrews 10:26-30

Remember, if we sin willfully after we have gained a full knowledge of the Truth, there can be no further sacrifice for sin;

Hebrews 10:39

But we do not belong to those who draw back, to their Ruin, but to those who have faith, to the saving of their souls.

Treasury of Scripture Knowledge

Summary

Because he should have remained in the city of his refuge until the death of the high priest: but after the death of the high priest the slayer shall return into the land of his possession.

After the death

Bible References

He should

John 15:4
Remain united to me, and I will remain united to you. As a branch cannot bear fruit by itself, unless it remains united to the vine; no more can you, unless you remain united to me.
Acts 11:23
On coming there he saw to his great joy these tokens of the loving-kindness of God, and encouraged them all to make up their minds to be faithful to the Lord--
Acts 27:31
When Paul said to the Roman Officer and his men: "Unless the sailors remain on board, you cannot be saved."
Hebrews 3:14
For we now all share in the Christ, if indeed we retain, unshaken to the end, the confidence that we had at the first.
Hebrews 6:4
For if those who were once for all brought into the Light, and learned to appreciate the gift from Heaven, and came to share in the Holy Spirit,
Hebrews 10:26
Remember, if we sin willfully after we have gained a full knowledge of the Truth, there can be no further sacrifice for sin;

After the death

Hebrews 9:11
But, when Christ came, he appeared as High Priest of that Better System which was established; and he entered through that nobler and more perfect 'Tabernacle,' not made by human hands--that is to say, not a part of this present creation.