In many congregations, this prayer is said on the Shabbat preceding Shavuot and Tishah b’Av.

Parent of mercy
Dwelling on highly
In myriad mercy
Will take account of, in mercy,
The pious and the upright and the pure
The holy congregations
Who gave their lives sanctifying the Name.

They were loved and adored in their lives;
And in their deaths they were not divided.
Swifter than eagles, Stronger than lions,^[1] II Samuel 1:23. 
To do the will of their Maker and the wish of their Fortress.

May our God remember them for good with all the remnant of the world’s righteous.
And avenge for our eyes the innocent blood of God’s servants spilled.

As is written in the Teaching of Moses the man of God —
O nations, acclaim God’s people!
For the blood of God’s people God will avenge;
Turn vengeance upon God’s adversaries,
And cleanse the land [for] God’s people.^[2] Deuteronomy 32:43. 

And by the hands of Your servants the prophets it is written, saying —
And I will treat their blood as innocent,
that which I have not treated innocent before;
and Adonai dwells in Ẓion.^[3] Joel 4:21. 

And in the holy writings it is said —
Why do the nations say,
“Where is their God?
Let the nations know before our eyes
That You will avenge the spilled blood of Your servants.^[4] Psalms 79:10. 

And it says —
For the One who pays back bloodshed remembers them;
Does not forget the cry of the afflicted.^[5] Psalms 9:13. 

And it says —
Judging upon the nations filling up corpses,
Smiting heads of the whole earth;
From the stream on the way drinking,
Thus holding head up high.^[6] Psalms 110:6-7.