Rembrandt's painting was based on the parable of the prodigal son, one of 3 'lost and found' stories that Jesus told. The other 2 are the lost sheep and the lost coin.
All 3 were told in respone to religious people grumbling that Jesus "welcomes sinners and eats with them". All 3 are parables of grace. The shepherd seeks his lost sheep until he finds it. The woman sweeps the house searching for her lost coin until she finds it. The father runs to meet and embrace his lost son. The shepherd, the woman and the father celebrate their joy with friends, neighbours and family. Neither the sheep, the coin, nor the returning son had done anything to deserve being found. The emphasis in all 3 stories is on the one who seeks what is lost and oveflows with joy at the finding. The seeking shepherd, woman and father show us something about the nature of God.
In Henri Nouewen's book "The Return of the Prodigal Son" he reflects on the father's hands as shown in Rembrandt's painting. The two hands are different from each other.
“The father’s left hand touching the son’s shoulder is strong and muscular. The fingers are spread out and cover a large part of the prodigal son’s shoulder and back. I can see a certain pressure, especially in the thumb. That hand seems not only to touch, but, with its strength, also to hold. Even though there is a gentleness in the way the father’s left hand touches his son, it is not without a firm grip.
How different is the father’s right hand! This hand does not hold or grasp. It is refined, soft, and very tender. The fingers are close to each other and they have an elegant quality. It lies gently upon the son’s shoulder. It wants to caress, to stroke, and to offer consolation and comfort. It is a mother’s hand…
As soon as I recognized the difference between the two hands of the father, a new world of meaning opened up for me. The Father is not simply a great patriarch. He is mother as well as father. He touches the son with a masculine hand and a feminine hand. He holds, and she caresses. He confirms and she consoles. He is, indeed, God, in whom both manhood and womanhood, fatherhood and motherhood, are full present. That gentle and caressing right hand echoes for me the words of the prophet Isaiah: “Can a woman forget her baby at the breast, feel no pity for the child she has borne? Even if these were to forget, I shall not forget you. Look, I have engraved you on the palms of my hands.”