The brothers Simon and Jude Thaddeus traveled together for some time after the dispersion of the Apostles. Simon headed toward the Black Sea and Scythia, while Thaddeus went toward the East, where he likely encountered Thomas and accompanied him for a stretch. He was later sent by Thomas with a letter to the King of Edessa, named Abgar.
When Thaddeus reached the king, the latter saw the luminous face of Jesus beside the Apostle and bowed down profoundly. Through the laying on of his hands, Thaddeus healed King Abgar of leprosy. After having healed and converted many in Edessa, he set out with his companion, Silas, through the lands that Jesus had visited and reached Egypt by way of Arabia. During this journey, the Apostle was able to baptize many in Kedar; entire populations embraced the faith.
The Apostle Simon headed to the country of the Persians after the death of Mary. He took the disciple Abdias and several others as companions. Later, Abdias became the Bishop of Babylon. By God's disposition, the two brothers met again in a military camp and made their way to a great city (Babylon). Here, things went very well for them. I have seen many things happen of which I now have only a vague idea.
I remember that in a meeting, in the presence of the king, the idolatrous priests rose up against the Apostle. Some of them carried a number of arm-length vipers in a basket, while others held them in their hands. These vipers were rounded, like eels, but thinner; they had round little heads, and their open jaws displayed sharp little tongues, like lancets, in a menacing posture. The priests threw them at the Apostle; but I saw that they flew back like arrows against the very people who had brought them. They bit them, and the priests cried out and wailed until the Apostle commanded the serpents not to harm them. I saw that many were converted, and the king himself with them.
The Apostles left that place, went to another city, and stayed at the house of a Christian. I saw a tumult arise in the city, and the two Apostles, along with the Christian, were led to a temple where there were several idols mounted on wheels. A tumultuous crowd had gathered inside and outside the temple.
I remember seeing the idols collapse, destroyed, and debris falling from the temple. As a consequence of this, the two Apostles were mistreated by the people, who, using all kinds of weapons and with the help of the idolatrous priests, wounded the holy Apostles until they were left dead. I saw how they split Apostle Thaddeus's head into two parts, right through the middle of his face, with an axe that a man carried in his belt. A celestial light and vision appeared over the holy martyr. The bodies of both Apostles came to rest in St. Peter's Basilica in Rome.