Related do Rosz ha-Szana 2:1

Formerly they used to accept the testimony of the new moon from everyone. On one occasion the Boethoseans asked two witnesses that they were coming and misleading the scholars because the Boethobeans only admitted that the Feast of Weeks came after the Sabbath. One came and made his statement and went away. [Then] the second came and said: I went up the Adummim ridge. Then I saw him lying between two rocks; his head was like a calf, his ears like a kid. I saw him, got scared, and fell backwards; and behold, extras were wrapped on my belt. They said to him: The money is given to you, but those who paid you should come and be flogged. What made you decide to give it up? He said to them: Because I have heard that the Boethosaians are eager to come [and] mislead the scholars, I say: It is better that I go and inform the scholars.

(Chapter 2 in the Erfurt manuscript) If one does not know him, his witnesses are sent with him, even on the Sabbath. An incident of R. Nehorai going to Usha with the Witness on the Sabbath and bearing witness for him.