Is the reward paid for relaying employees' words about their manager permissible or forbidden (halal or haram)?

It is not permissible to convey colleagues' words to the manager, as this involves backbiting (namima) and spying (tajassus), and the reward for it is ill-gotten wealth (haram mal). Backbiting is a major sin, and it is the conveying of speech with the intention of causing mischief, or revealing what is disliked to be revealed by any means. Conveying information to the manager is a breach of trust, an attempt to cause mischief, and an unlawful act of spying. The dispraise of backbiting and spying has been mentioned in religious texts, including: "A backbiter will not enter Paradise," and "The other used to walk with backbiting," and "Beware of suspicion, for suspicion is the falsest of speech; and do not seek out secrets (tahassasu), nor spy (tajassasu)." Furthermore, whoever listens to the conversation of people while they are averse to him, molten lead will be poured into his ears on the Day of Judgment.