When Saul died in battle (1 Sam. 31:1ff.), the man that reported it to David identifies himself as "the son of an alien, an Amalekite" (2 Sam. 1:13). He calls himself a resident alien (ger), rather than a foreigner (nekhar). He is also referred to as na'ar (2 Sam. 1:5, 6, 13), which is typically translated "young man;" but it has another meaning that makes more sense in context, which is "young soldier." He had to be at least twenty to serve in the military (Num. 1:3). This suggests that resident aliens could serve in the military in ancient Israel.
- James K. Hoffman, The Immigration Crisis 107-08 (2009).