As Rabbi Yochanan Ben Zakai lay sick on his deathbed, his students came to see him. When he saw them, he began to cry. They asked him why he was crying, and he replied: “There are two roads before me, one to Gan Eden and one to Gehinom, and I don’t know on which road they will lead me” (Berachos 28b).
The Chasam Sofer asks: Why did he cry in the presence of his students? Isn’t it more appropriate to weep tears of Teshuva in private? Furthermore, did the great Rabbi Yochanan Ben Zakai truly doubt whether he would enter Gan Eden?
Rather, the Chasam Sofer explains, Rabbi Yochanan Ben Zakai knew that his place was in Gan Eden. However, when he saw his students, those who ought to continue in his path, he doubted whether after his passing they would indeed do so; thus, he wept specifically before them, saying, “I don’t know on which road they”—my students—“will lead me.”
When the students sensed their teacher’s pain, they asked him to bless them before his passing. He declared: “May G–d grant that your fear of Heaven equal your fear of beings of flesh and blood.”
In other words, his students were asking him to bless them and endow them with the strength to be able to continue in his path even after his passing. To this he responded, “May G–d grant that your fear of Heaven equal your fear of beings of flesh and blood.” What he meant was: Even after my soul departs from my body, and I will be in a state of “heaven,” I hope that you will treat me as “a being of flesh and blood,” just as if I were still alive.Iyunim U’biurim Bimegilas Esther, p. 56.
The lesson for Chassidei Chabad today is clear.
The key to maintaining our Hiskashrus after Gimmel Tammuz is relating to the Rebbe with the same serious devotion as if he were still alive. The Rebbe has surely granted us the ability to accomplish this, for indeed, the Rebbe is still with us just as he was before Gimmel Tammuz, albeit in a hidden fashion. (For explanation, see here, where the Rebbe said as much after the passing of the Previous Rebbe.)
Thus, reminding ourselves of this inner reality endows us with the strength to maintain our deep bond with the Rebbe despite his (temporary) concealment. Also , see here for a similar teaching.