Semachoth, chap. 9.
It is unlawful for one to enter a banqueting-house for thirty days after the death of a relative; but he must refrain from so doing for twelve months after the demise of either father or mother, unless on the behest of some higher requirement of piety.
Ibid.
But I know not whether there are thirty righteous men here and fifteen in the land of Israel, or vice versâ.
Chullin, fol. 92, col. 1.
Thirty days in a year are equivalent to a whole year.
Niddah, fol. 44, col. 2.
"Moses, thou didst say unto me, 'What is Thy name?' And now thou dost say, 'Neither hast Thou delivered Thy people at all.' Now shalt thou see what I will do to Pharaoh (Exod. v. 23, vi. 1), but not what I am about to do to the thirty-one kings."
Sanhedrin, fol. III, col. 1.