Since verb form indicates the person,
gender, and number of the subject any use of a subject pronoun is considered redundant. If, however, you want to emphasize or contrast two objects Arabic allows you to use the subject pronoun in such a linguistic environment.
**أنا ذهبتُ إلی المکتبةِ وهُم ذهبوا إلی المطعم ِ.**
I went to the library and they went to the restaurant.