Spy Wednesday is traditionally the day on which Judas went to betray Christ in exchange for thirty pieces of silver. There's a fascinating Middle English poem about Judas which is also one of the earliest ballads in English; it dates from about 1300.
This poem shows us a surprisingly sympathetic version of Judas. It tells the story that he is sent by Jesus to buy food for the apostles with thirty pieces of silver, but on the way he meets his wicked sister who berates him for supporting a false prophet. She persuades him to fall asleep, and when he wakes up the silver has been stolen. He is taken before Pilate, who asks him what it will take to make him betray Christ, and Judas says he would only do so to regain the thirty pieces of silver. Then, in characteristic ballad fashion, the scene cuts to Christ and the apostles dining together at the Last Supper. As in the Gospel account, Christ tells them that one of them will betray him, and Judas denies it (with what I think may be a deliberately ambiguous assertion of the kind popular in ballads and medieval romance, along the lines of Isolde's "only the beggar who carried me across the river touched me"). The repetition of whole lines and the use of dialogue is very reminiscent of later ballads, and Judas' confusion and anguish comes across well.
Here's a modernised version. I made up the verse divisions, but they seem to work...
It was upon a Sheer Thursday* that our Lord arose,
Full mild were the words he spake to Judas:
"Judas, thou must to Jerusalem our meat for to bugge*;
Thirty plate of silver thou bear upon thy rugge*.
When thou comest far in the broad street, far in the broad street,
Some of thine kinsmen there thou mayst meet."Thirty plate of silver thou bear upon thy rugge*.
When thou comest far in the broad street, far in the broad street,
He met with his sister, the swikele* woman:
"Judas, thou were worthy be stoned with stone;
"Judas, thou were worth be stoned with stone,
For the false prophet that thou believest upon."
"Be still, lief sister, may thine heart break!
Wist this mine Lord Christ, full well he would be wreke.*"
"Judas, go thou on the rock, high upon the stone;
Lay thy head on my bosom, sleep thou thee anon."
As soon as Judas of sleep was awake,
Thirty plate of silver from him were i-take.
He drow himself by the top that all it laved blood* -
The Jews out of Jerusalem wenden he were wod.
To him came the riche Jew that hight Pilatus:
"Wilt thou sell thy Lord that hight Jesus?"
"I nulle sell my Lord for none cunnes eiste*,
But it be for the plate that he me betaiste*."
"Wilt thou sell thy Lord Christ for any kind of gold?"
"Nay, but it be for the plate that he habben wold."
To him come our Lord God as his postles sat at meat.
"How sit ye postles, and why nulle ye eat?
"How sit ye postles, and why nulle ye eat?
I am bought and sold today for our meat."
Up stood him Judas, "Lord, am I that frec?
I was never in the stede where men thee evil spake."
Up him stood Peter and spake with all his might:
"Though Pilatus him come with ten hundred knights,
"Though Pilatus him come with ten hundred knights,
Yet I will, Lord, for thy love fight."
"Still thou be, Peter! Well I thee know:
Thou wilt forsake me thrice ere the cock him crow."
* Sheer Thursday, another name for Maundy Thursday. So, not Spy Wednesday!
* buy
* back
* when you come...
* wicked
* if my Lord Christ knew this, he would have his revenge
* he tore his hair until his head was covered in blood
* I will not sell my Lord for any kind of possessions
* except the money he entrusted to me