Hadith.3292 - And Sama'ah ibn Mehran narrated from Abu Baseer, from Abu Abdullah (as), who said
"There is no harm in the testimony of a guest if he is chaste and upright."
Imam (as) also said: "The testimony of an employee for his employer is disliked, but there is no harm in his testimony for someone else, and there is no harm in his testimony for the employer after leaving his service."