Halacha:

Lashon Harah 

Machshava:

Lag BaOmer 

Personalities:

Rebbi Shimon bar Yochai 

References: Shabbat: 33B  

Description

Divulging information under duress of torture, putting others at risk, and the extent of lashon hara. (Sources: Shabbos 33b, and Rashi and Tosfos ad loc.; Magen Avraham 156:2, and Machatzis HaShekel ad loc.; Rambam Deios 7:5)