Reference: Siyar A’laam an-Nubalaa – Volume 15, Page 395
Abu Maysarah Ahmad ibn Nazaar said to a man:
O my brother, the benefit of getting together is [that it reminds us] to supplicate [for one another].
So should you remember me, then supplicate for me, and if I remember you, I shall supplicate for you; and [in this manner] we shall be as if we have met up, even if we haven’t [actually done so].