Hora’ah – הוראה – Teaching
Whenever you pray you should have in mind that you bind yourself to the Tzaddikim of the generation. They alone know how to elevate each prayer to its proper place.
Likutey Moharan I, 2:6
The connection made available through the tzaddik even extends past the his death. The Talmud tells how when Caleb was on his way with the spies Moses sent, he separated himself from the others and went to the Cave of Machpelah to visit the graves of Abraham, Isaac and Jacob. There he prayed to G-d, and he asked the souls of these tzaddikim to arouse G-d’s mercy, so that G-d would save him from becoming involved in the rebellion that would be led by the other spies.
“Caleb held aloof from the plan of the spies and went and prostrated himself upon the graves of the patriarchs, saying to them, “My fathers, pray on my behalf that I may be delivered from the plan of the spies.” (As for Joshua, Moses had already prayed on his behalf; as it is said: And Moses called Hoshea the son of Nun Joshua, meaning, May Yah save thee from the plan of the spies. That is the intention of what is written: But My servant Caleb, because he had another spirit with him.”
Talmud, Sotah 34b
“It is certainly permissible to pray to G-d for a blessing at the gravesite of a tzaddik, in the merit of the tzaddik. In addition one may directly address the soul of the tzaddik, beseeching him to arouse mercy in heaven. The Zohar writes that the tzaddik can more effectively arouse Divine mercy after his death than previously. (See chapter 27 in Igeret Hakodesh of Sefer Hatanya). When one goes to pray at the gravesite of a tzaddik, it is as if he is entering into yechidus (“private consultation”) with that tzaddik. Thus, it is customary to recite chapter 33 in Psalms at the gravesite. This chapter begins with the verse, Ranenu tzaddikim baHashem, “May the tzaddikim rejoice in Hashem.” The verse refers to tzadikkim in the plural form, which is understood to refer to the union of the lower tzaddik — the soul of the person who comes to pray at the gravesite — and the higher tzaddik — the deceased tzaddik. When a person prays at the gravesite of the tzaddik, the two souls unite to arouse Divine mercy and to bring down blessing.”
Prayer at a Tzaddik’s Grave, rabbi Yitzchak Ginsburgh, http://www.inner.org/responsa/leter2/resp51.htm
“And whatsoever ye shall ask in my name, that will I do, that the Father may be glorified in the Son.”
“If ye shall ask any thing in my name, I will do it.”
“Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you.”
“And in that day ye shall ask me nothing. Verily, verily, I say unto you, Whatsoever ye shall ask the Father in my name, he will give it you. Hitherto have ye asked nothing in my name: ask, and ye shall receive, that your joy may be full. … At that day ye shall ask in my name: and I say not unto you, that I will pray the Father for you.”