Part 1: Graveside Prayers
The custom of visiting graves is an ancient one. Jacob buried Rachel on the road for this very purpose (sources 1 & 2). Caleb visited the Cave of Machpelah when spying on the Land of Canaan (source 3). The Zohar gives a fascinating explanation about the process that takes place when we pray at the gravesite of a saintly person.
Part 2: Burial in the Diaspora
The Midrash says that Moses was buried in the desert in order to remain with his flock (source 5).
The Rebbe explains that this is a basic feature of every true Jewish leader — they remain with their people in life and in afterlife. For this very reason, the Chabad Rebbes were always buried in the Diaspora.
Part 3: Holy Land Connection
The Talmud says that we should face the Land of Israel when praying (source 6).
The Rebbe explains that the best form of prayer is one that takes place within the spiritual ‘properties’ of the Land of Israel—and the resting place of a tzaddik has just those qualities, making prayer there especially potent.
Part 4: More Than Israel
The Rebbe points out that in our day, a prayer at the Rebbe’s gravesite is more powerful than a prayer in the Land of Israel itself.
A Video: The Rebbe at the Ohel.