Berachoth, fol. 40, col. 1.

He who eats unripe dates and does not wash his hands will for thirty day be in constant fear, without knowing why, of something untoward happening.

P’sachim, fol. 111, col. 2.

The Rabbis have taught that the lighter kind of excommunication is not to last less than thirty days, and censure not less than seven.  The latter is inferred from what is said in Num. xii. 14, “If her father had but spit in her face, should she not be ashamed seven days?”

Moed Katon, fol. 16, col. 1.

If we meet a friend during any of the thirty days of his mourning for a deceased relative, we must condole with him but not salute him; but after that time he may be saluted but not condoled with.  If a man (because he has no family) re-marries within thirty days of the death of his wife, he should not be condoled with at home (lest it might hurt the feelings of his new partner); but if met with out of doors, he should be addressed in an undertone of voice, accompanied with a slight inclination of the head.

Ibid., fol. 21, col. 2.

During the thirty days of mourning for deceased friends or relatives, the bereaved should not trim their hair; but if they have lost their parents, they are not to attend to such matters until their friends force them to do so.

Ibid., fol. 22, col. 2.

“And Haman told them of the glory of his riches and the multitude of his children” (Esth. v. 11).  And how many children were there?  Rav said thirty; ten had died, ten were hanged, and ten went about begging from door to door.  The Rabbis say, “Those that went about begging from door to door were seventy; for it is written (1 Sam. ii. 5), ’They that were full have hired themselves for bread.’”

Meggillah, fol. 15, col. 2.

When Rabbi Chanena bar Pappa was about to die, the Angel of Death was told to go and render him some friendly service.  He accordingly went and made himself known to him.  The Rabbi requested him to leave him for thirty days, until he had repeated what he had been learning; for it is said, “Blessed is he who comes here with his studies in his hand.”  He accordingly left, and at the expiration of thirty days returned to him.  The Rabbi then asked to be shown his place in Paradise, and the Angel of Death consented to show him while life was still in him.  Then said the Rabbi, “Lend me thy sword, lest thou surprise me on the road and cheat me of my expectation.”  To this the Angel of Death said, “Dost thou mean to serve me as thy friend Rabbi Yoshua did?” and he declined to intrust the sword to the Rabbi.

Kethuboth, fol. 77, col. 2.

If a man says to a woman, “Thou art betrothed to me after thirty days,” and in the interim another comes and betroths her, she is the second suitor’s.

Kiddushin, fol. 58, col 2.