Prayers and excerpts from the Baha'i Writings
Most Baha'i prayer books have a section on prayers for those who have passed away from this "world of dust", or you can go here to find lots of them. Remember that only the Prayer for the Dead is obligatory and must be said in accordance with instructions.
The Baha'i Writings on the life after death and immortality are appreciated by just about everybody, whether they are Baha'is or not. Here are a few:
"To consider that after the death of the body the spirit perishes is like imagining that a bird in a cage will be destroyed if the cage is broken, though the bird has nothing to fear from the destruction of the cage." - Abdu'l-Bahá, Some Answered Questions, p. 228
"O SON OF THE SUPREME! I have made death a messenger of joy to thee. Wherefore does thou grieve? I made the light to shed on thee its splendour. Why dost though veil thyself therefrom?" - Baha'u'llah
'Ab'dul-Baha grieved for His Father even as we grieve for those we love who have left us, but He says,
"... I am consoled by the realization that the worlds of God are infinite; that though they were deprived of this existence, they have other opportunities in the life beyond, even as Christ has said, "In my Father's house are many mansions". They were called away from the temporary and transferred to the eternal; they abandoned this material existence and entered the portal of the spiritual world. Foregoing the pleasures and comforts of the earth, they now partake of a joy and happiness far more abiding and real, for they have hastened to the Kingdom of God.
Baha'u'llah says: "The world beyond is as different from this world as this world is different from that of the child while still in the womb of its mother. When the soul attaineth the Presence of God, it will assume the form that best befitteth its immortality and is worthy of its celestial habitation." - Baha'u'llah