The purpose of a sewing needle is to attach two objects to each other. In reference to the service of G-d, this corresponds to tying together the higher and lower realms, a process that is achieved through the soul's descent into the physical body in order to make a dwelling place for G-d in this world.

Because the soul is the vehicle that forges this connection, it is referred to as a "needle." Moreover, the soul's descent into the body represents a merging of higher and lower orders, since it is a manifestation of G-d Himself, clothed in the most physical aspect of creation - the body.

Specifically, in the use of a needle there are two components. The first is the point, which pierces the garment being sewn, while the second is the thread that is drawn through the hole. The combination of these two elements defines the process of sewing.

In our G-dly service, the point of the needle (that which penetrates the garment), alludes to a person's ability to nullify the gross materialism of the world and prepare it to be a receptacle for divinity. The thread (the actual medium of sewing), refers to Torah and mitzvos, through which the implementation of G-dliness is realized in this world.

Sefer HaSichos 5750, Vol. 2, p. 704