New Revised Standard Version
If he is able to fight with me and kill me, then we will be your servants; but if I prevail against him and kill him, then you shall be our servants and serve us.”

Contemporary English Version
If he can kill me, our people will be your slaves. But if I kill him, your people will be our slaves.

New American Bible
If he beats me in combat and kills me, we will be your vassals; but if I beat him and kill him, you shall be our vassals and serve us.”

Douay-Rheims Bible
If he be able to fight with me, and kill me, we will be servants to you: but if I prevail against him, and kill him, you shall be servants, and shall serve us.

If he be able to fight with me, and kill me, we will be servants to you: but if I prevail against him, and kill him, you shall be servants, and shall serve us.

and serve us

1 Samuel 11:1 And it came to pass about a month after this, that Naas, the Ammonite, came up, and began to fight against Jabes Galaad. And all the men of Jabes said to Naas: Make a covenant with us, and we will serve thee.