In the year 5679 (1918), it was impossible to obtain etrogim in Russia. These were the turbulent days following World War I, and the borders were closed. Only the Rebbe Rashab, the fifth Rebbe of Chabad, who was then living in Rostov, had an etrog. Naturally, all the Jews of the city came to make the blessing over the Reb-be's etrog.
During Chol HaMoed, large numbers of Jews began arriving from the surrounding towns to make the blessing over the etrog. One chassid traveled hundreds of kilome-ters. Deeply moved, he entered and held the etrog as though in a dream.
When he finished making the blessing, the chassid exclaimed with joy and satisfac-tion:
"Ah! Thank G-d!"
The Rebbe then said:
"May Hashem grant that the joy of the mitzvah illuminate the entire year."