Esther 9:27

the Jews established and made a custom for themselves and for their descendants and for all those who allied themselves with them, so that they would not fail to celebrate these two days according to their regulation and according to their appointed time annually.

Esther 8:17

In each and every province and in each and every city, wherever the king’s commandment and his decree arrived, there was gladness and joy for the Jews, a feast and a holiday. And many among the peoples of the land became Jews, for the dread of the Jews had fallen on them.

Isaiah 56:3

Let not the foreigner who has joined himself to the Lord say,
“The Lord will surely separate me from His people.”
Nor let the eunuch say, “Behold, I am a dry tree.”

Isaiah 56:6

“Also the foreigners who join themselves to the Lord,
To minister to Him, and to love the name of the Lord,
To be His servants, every one who keeps from profaning the sabbath
And holds fast My covenant;

Zechariah 2:11

Many nations will join themselves to the Lord in that day and will become My people. Then I will dwell in your midst, and you will know that the Lord of hosts has sent Me to you.

Deuteronomy 5:3

The Lord did not make this covenant with our fathers, but with us, with all those of us alive here today.

Deuteronomy 29:14-15

“Now not with you alone am I making this covenant and this oath,

Joshua 9:15

Joshua made peace with them and made a covenant with them, to let them live; and the leaders of the congregation swore an oath to them.

1 Samuel 30:25

So it has been from that day forward, that he made it a statute and an ordinance for Israel to this day.

2 Samuel 21:1-2

Now there was a famine in the days of David for three years, year after year; and David sought the presence of the Lord. And the Lord said, “It is for Saul and his bloody house, because he put the Gibeonites to death.”

Esther 9:21

obliging them to celebrate the fourteenth day of the month Adar, and the fifteenth day of the same month, annually,

Zechariah 8:23

Thus says the Lord of hosts, ‘In those days ten men from all the nations will grasp the garment of a Jew, saying, “Let us go with you, for we have heard that God is with you.”’”

Treasury of Scripture Knowledge

Summary

The Jews ordained, and took upon them, and upon their seed, and upon all such as joined themselves unto them, so as it should not fail, that they would keep these two days according to their writing, and according to their appointed time every year;

Bible References

And upon their seed

Deuteronomy 5:3
The Lord did not make this covenant with our fathers, but with us, with all those of us alive here today.
Deuteronomy 29:14
“Now not with you alone am I making this covenant and this oath,
Joshua 9:15
Joshua made peace with them and made a covenant with them, to let them live; and the leaders of the congregation swore an oath to them.
1 Samuel 30:25
So it has been from that day forward, that he made it a statute and an ordinance for Israel to this day.
2 Samuel 21:1
Now there was a famine in the days of David for three years, year after year; and David sought the presence of the Lord. And the Lord said, “It is for Saul and his bloody house, because he put the Gibeonites to death.”

All such

Esther 8:17
In each and every province and in each and every city, wherever the king’s commandment and his decree arrived, there was gladness and joy for the Jews, a feast and a holiday. And many among the peoples of the land became Jews, for the dread of the Jews had fallen on them.
Isaiah 56:3
Let not the foreigner who has joined himself to the Lord say,
“The Lord will surely separate me from His people.”
Nor let the eunuch say, “Behold, I am a dry tree.”
Zechariah 2:11
Many nations will join themselves to the Lord in that day and will become My people. Then I will dwell in your midst, and you will know that the Lord of hosts has sent Me to you.
Zechariah 8:23
Thus says the Lord of hosts, ‘In those days ten men from all the nations will grasp the garment of a Jew, saying, “Let us go with you, for we have heard that God is with you.”’”