I have given unto thy master's son - Unless Ziba had been servant of Jonathan, this seems to refer to Micha, son of Mephibosheth, and so some understand it; but it is more likely that Mephibosheth is meant, who is called son of Saul instead of grandson. Yet it is evident enough that the produce of the land went to the support of Micha, (see 2 Samuel 9:10;), for the father was provided for at the table of David; but all the patrimony belonged to Mephibosheth.
Saul‘s servant - Josephus calls him one of Saul‘s freedmen. The difference this would make in Ziba‘s position would only be that instead of paying in the fruits of the confiscated land to David, he would have to pay them to Mephiboseth.