In my community, some people said that if a person works for some one (paid by institution or boss for his services), then that means that he sold his luck to that institution or his boss. They further explain: What Allah had decreed for him is now given to his boss, and now his boss will determine how much he gives him. Please guide me regarding this view because these people discourage other people from getting jobs and favor opening your own business, even if it is very small. May Allaah reward you.

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.

Among the most important basic principles of faith is to believe that all matters are in the Hands of Allaah alone, and it is Allaah alone Who predestines and decrees, and none can prevent what Allaah has willed to bestow, and none can bestow what Allaah has willed to prevent. Also, the will of the creation is not independent from the Will of Allaah and His Predestination. Whatever provision Allaah has predestined for a person, then that person will surely get it in its totality, and whatever provision Allaah prevented from someone, then that person will not get anything from it at all.

The Prophet said, "O people, fear Allaah and seek lawful provision! Indeed, one's soul shall not die until it would have consumed its (designated) provision even if it comes to him late, so fear Allaah and seek lawful provision. Take what is lawful for you and refrain from what is forbidden to you." [Ibn Maajah - Al-Albaani graded it Saheeh (sound)]

As regards what you have quoted in your question, it is ambiguous and not clear. As for those people's statement, “What Allaah had decreed for him is now given to his boss, and now his boss will determine how much he gives him;” if what is meant by this is that Allaah may have made the boss a cause for the provision to reach the employee, then this is correct. However, this does not contradict the fact that it is Allaah alone Who gives and Who prevents (provision from people), as Allaah predestines and decrees with some causes that He makes in His creation. Nonetheless, the will of the boss – like the will of the children of Aadam (Adam) in general – is dependent on the Will of Allaah and His universal Will, so if Allaah willed that this salary will be for that employee, then no boss nor anyone else will prevent it (from him), and vice versa.

On the other hand, provision is not only restricted to the salary in principle; anything that a person gets, which benefits him, is provision, so the salary that a person gets is a portion of his livelihood and not his entire livelihood. Also, someone’s provision is what a person gets, and whatever he does not get is not his provision in principle, so it is not correct to say that a person sells his livelihood before he gets it.

As regards preferring trade over a profession (job), then some scholars hold the view that trade is the best livelihood. Al-Kasb, authored by Muhammad ibn al-Hasan, reads:

“Then our scholars differed in opinion about trade and agriculture, some of them said: trade is better, as Allaah says (what means): {…and others traveling throughout the land seeking [something] of the bounty of Allaah…} [Quran 73:20]

What is meant is spreading in the earth for trade, so it was mentioned in the verse before jihaad, which is the hump of the religion of Islam. It is for this reason that ‘Umar said, 'If I were to die on my saddle setting out in the land seeking Allaah’s bounty, then that would be more beloved to me than fighting as a mujaahid in the way of Allaah.' Also, the Prophet said: 'The trustworthy trader will be with the dutiful and honorable people on the Day of Judgment.'”

Fat-h Al-Baari by Ibn Hajar, reads, “The scholars differed in opinion regarding the best provision; al-Maawardi said, 'The sources of provision are agriculture, trade and crafts; the Shaafi’i School holds the view that the best of them is trade ... the correct opinion is that they are of various degrees, and it may vary depending on the circumstances and people; Allaah knows best.”

Therefore, according to the scholars who held the view that trade is the best provision, then working in trade is better than working as an employee (having a job). The preference of trade over a profession is strengthened by the fact that working in trade is more beneficial to the people – in general – and it is safer in avoiding the favor of the employer and his authoritarianism and other hustles that may hurdle the job. Besides, trade is the biggest door of livelihood – as Musaddad reported in his Musnad from Nu’aym ibn ‘Abdur-Rahmaan who said, "I was informed that the Prophet said, 'Nine-tenths of livelihood is in trade.' Nu’aym said, 'Earning the remaining one-tenth is in sheep [and goats].' Al-Busayri said, 'This chain of narrators is weak because Nu’aym ibn Abdur-Rahmaan is unknown.'” 

It is a Mursal hadeeth (i.e. a Hadeeth narrated by a Tabi'i [successor of the Prophet's Companions]) as Nu’aym was not confirmed to be a Companion of the Prophet . Therefore, working in trade makes a person more capable of giving charity and doing good, and also, one relies upon Allaah in gaining a livelihood by trade more than when doing a job.

It may be also said that what is better between trade and employment or other jobs varies depending on the people and their circumstances, as highlighted by Ibn Hajar .

Allaah Knows best.