This is an idiom that means "began to act." Whether Peter was sitting or standing when he decided to act is not important. AT: "started out" (See: [[rc://en/ta/man/translate/figs-idiom]])
"only the linen cloths." This refers to the cloths that had been wrapped around Jesus' body when he was buried in [Luke 23:53](../23/52.md). It is implied that the body of Jesus was not there. AT: "the linen cloths in which Jesus' body had been wrapped, but Jesus was not there" (See: [[rc://en/ta/man/translate/figs-explicit]])