135 Rosh Hashanah 1/5-8

(5) Regardless of whether the moon was clearly visible or not clearly visible, they desecrate the Shabbat for it; Rabbi Yosei says: If it was clearly visible, they do not desecrate the Shabbat for it.

(6) It happened once, that more than forty pairs of witnesses passed through on [Shabbat] and Rabbi Akiva detained them in Lod. Rabban Gamliel [then] sent word to him, [saying], "If you detain the multitudes [from passing through on Shabbat to testify], it will come out that you will be causing them to stumble in the future [and they will not come to testify about the new moon even when there is a need for it]."

(7) If a father and son saw the new moon, they must [both] go to the court [that will take their testimony to potentially confirm that sighting and ratify the new month accordingly]; not that they may be combined [together to act as witnesses], but rather that in the event that one of them be declared unfit, the other may join [to give evidence] with another [witness]. Said Rabbi Shimon, "A father and his son, and all relatives, are fit to [join together and] give evidence about the [appearance of the] new moon." Said Rabbi Yose, "It once happened that Toviah the physician, his son, and his freed slave saw the new moon in Jerusalem, [and when they testified before them,] the Kohanim [members of the priestly caste, a subgroup of tribe of Levi, which is uniquely responsible for maintaining and carrying out the sacrificial services in the Temple] accepted him and his son [as witnesses together], but declared his slave unfit; but when they came to [testify before] the court, they accepted him and his slave [as witnesses together], but declared his son unfit."

(8) These are considered unfit [witnesses]: gamblers with dice, those that lend with interest, pigeon racers, those who trade in the produce of the Sabbatical year, and slaves. This is the rule: all testimony that a woman is not fit to give, these [above] are also not fit to give.