Farewell, thou child of my right hand, and joy;
 My sin was too much hope of thee, lov'd boy.
Seven years thou wert lent to me, and I thee pay,
 Exacted by thy fate, on the just day.
Jonson seems to be saying farewell to a child, although “child of my right hand” is a similar to the translation behind the Hebrew name Benjamin. 
 The “child of my right hand” could also allude to a work by Jonson and not an actual child, as a poem can be “born” as it is written by the hand.
On My First Son