Reb Shimon said about Lag b'Omer, האי קאי ברשותי יומא, "This day is mine." Hashem gave this day to Reb Shimon, and therefore, many miracles occur on this day. The Zohar (Idra 296) says that when Reb Shimon was buried in Meron, a bas kol announced, "In your merit, many kitrugim [harsh decrees] are silenced on this day." This occurs every year on Lag b'Omer. It is a day when the kitrugim are silenced, and Hashem sends all types of salvations to Bnei Yisrael.
The Beis Aharon writes, 'ה הוא ת"שהשי כשם לפחותים אפילו לכל י"רשב הוא י"רשב כך לכל, "Just as Hashem is for everyone, so is Reb Shimon for everyone, even for those who are at a low level." לכל, "for everyone," can also be translated as "for everything" because on Lag b'Omer, a person can receive everything he needs.
The Tur (428) teaches that Lag b'Omer is always on the same day of the week as Purim. About Purim, it states לו נותנים יד הפושט כל that whatever one asks for on this day is given to him— the same applies to Lag b'Omer. It is an auspicious time for tefillah, and whatever one requests will be given to him.
The Kozniter Magid zt'l (Tehilas Yisrael, Tehillim 42) writes, "The entire Sefirah we await Lag b'Omer because that is when there is a lot of rachamim." Lag b'Omer is a day of salvations – fortunate are those who invest in tefillah on this day.
