97.
Asked whether it was possible through faith and love to bring the New Revelation to the knowledge of those who have departed from this life without hearing of it, 'Abdu'l-Baha replied:--"Yes, surely! since sincere prayer always has its effect, and it has a great influence in the other world.

We are never cut off from those who are there.

The real and genuine influence is not in this world but in that other."-- Notes of Mary Hanford Ford: Paris, 1911.
On the other hand, Baha'u'llah writes:-- He who lives according to what is ordained for him--the Celestial Concourse, and the people of the Supreme Paradise, and those who are dwelling in the Dome of Greatness will pray for him, by a Command from God, the Dearest and the praiseworthy.

(Tablet translated by 'Ali Kuli _Kh_an).
When 'Abdu'l-Baha was asked how it was that the heart often turns with instinctive appeal to some friend who has passed into the next life, He answered:--"It is a law of God's creation that the weak should lean upon the strong.

Those to whom you turn may be mediators of God's power to you, even as when on earth.