I know a Muslim who calls himself Jaleel. Is it ok for others to call him Jaleel or should the name be called with Abdul?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is permissible to name someone after the common names which are among the Attributes and Names of Allaah, like Rasheed, Badee', Jaleel, and the like. However, it is more appropriate to add the word 'Abd' before the name, as the majority of the scholars consider that it is desirable to name after the names that imply servitude to Allaah, like 'Abdullaah and 'Abdur-Rahmaan and so forth.

Therefore, there is no harm, Allaah willing, to call this person by his name 'Jaleel'. Moreover, it is more appropriate to leave his name as it is without adding the word 'Abd', since this is the name that he was given at the first place, so that this would not cause any confusion which could lead to losing some rights. Lastly, it should be noted that it is forbidden to name after the names that are specific to Allaah, like Al-Khaaliq (The Creator) and Ar-Rahmaan (The Most-Merciful) and so on.

Allaah Knows best.