Esther 9:27

the Jews established and adopted [it] for themselves and for their offspring, and for all who joined them. They did not neglect {to observe} these two days every year as it was written and appointed to them.

Esther 8:17

In every province and city, wherever the king's edict and his law came, there was gladness and joy for the Jews, a banquet and a {holiday}, and many of the people from the country [were] posing as Jews because the fear of the Jews had fallen on them.

Isaiah 56:3

And do not let the {foreigner} [who] joins himself to Yahweh say, "Surely Yahweh will separate me from his people." And do not let the eunuch say, "Look! I [am] a dry tree!"

Isaiah 56:6

And the {foreigners} [who] join themselves to Yahweh to serve him and to love the name of Yahweh, to become his servants, every one who keeps [the] Sabbath, {so as not to profane} it, and those who keep hold of my covenant,

Zechariah 2:11

"Many nations will join themselves to Yahweh on that day, and they will be my people, and I will dwell in your midst. And you will know that Yahweh of hosts has sent me to you.

Deuteronomy 5:3

[It was] not with our ancestors [that] Yahweh made this covenant, [but with] these [of] us [who are] here alive today.

Deuteronomy 29:14-15

"Now I am not {making this covenant} and this oath {with you alone}.

Joshua 9:15

And Joshua made peace with them, and {he made a covenant with them} to allow them to live happily, and the leaders of the congregation swore [an oath] to them.

1 Samuel 30:25

So from that day and beyond, he made it a rule and a regulation for Israel until this day.

2 Samuel 21:1-2

There [was] a famine in the days of David [for] three years, year after year. And David {inquired of Yahweh}, and Yahweh said, "The bloodguilt [is] on Saul and on his household, because he killed the Gibeonites."

Esther 9:21

to impose on them to keep the fourteenth day of the month of Adar, and the fifteenth [day], {every year},

Zechariah 8:23

Thus says Yahweh of hosts: 'In those days ten men from {all the nations of every language} will take hold of the hem of a Judean man, 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
[It was] not with our ancestors [that] Yahweh made this covenant, [but with] these [of] us [who are] here alive today.
Deuteronomy 29:14
"Now I am not {making this covenant} and this oath {with you alone}.
Joshua 9:15
And Joshua made peace with them, and {he made a covenant with them} to allow them to live happily, and the leaders of the congregation swore [an oath] to them.
1 Samuel 30:25
So from that day and beyond, he made it a rule and a regulation for Israel until this day.
2 Samuel 21:1
There [was] a famine in the days of David [for] three years, year after year. And David {inquired of Yahweh}, and Yahweh said, "The bloodguilt [is] on Saul and on his household, because he killed the Gibeonites."

All such

Esther 8:17
In every province and city, wherever the king's edict and his law came, there was gladness and joy for the Jews, a banquet and a {holiday}, and many of the people from the country [were] posing as Jews because the fear of the Jews had fallen on them.
Isaiah 56:3
And do not let the {foreigner} [who] joins himself to Yahweh say, "Surely Yahweh will separate me from his people." And do not let the eunuch say, "Look! I [am] a dry tree!"
Zechariah 2:11
"Many nations will join themselves to Yahweh on that day, and they will be my people, and I will dwell in your midst. And you will know that Yahweh of hosts has sent me to you.
Zechariah 8:23
Thus says Yahweh of hosts: 'In those days ten men from {all the nations of every language} will take hold of the hem of a Judean man, saying, "Let us go with you, for we have heard [that] God [is] with you!" '"