About 15 men broke with Zwingli, and, while taking no specific action at that time, they regularly met together for prayer, fellowship and Bible study. During this time of waiting for direction from God, they sought religious connections outside of Zürich. Grebel wrote to both Andreas Karlstadt and Martin Luther in the summer of 1524, and to Thomas Müntzer in September. Karlstadt traveled to Zürich and met with them in October of that year. Despite apparent similarities, no connection between the Zürich radicals and Karlstadt ever came to fruition. In his letter to Müntzer, Grebel encouraged Müntzer in his opposition to Luther, but also reproached him for several errors he felt he was making. He urged Müntzer not to take up arms. The letter was returned to Grebel, having never reached Müntzer.