Shaykh Muqbil ibn Hadi al-Wadi‘i wrote:

Some of the fruits of belief in al-Qadr (Divine Decree) are:

1. Fulfilling the Worship of Allah: Belief in al-Qadr is one of the ways Allah has commanded us to worship him.

2. Strength of Faith: A believer in al-Qadr remains steadfast and unshaken, regardless of the hardships faced in the path of the truth.

3. Courage, Bravery, and Standing Firm: A believer in al-Qadr knows they will only die when their time has come and will only face trials and tribulations that are decreed for them, thus they remain unperturbed by harm, misfortune and calamities.

4. Tranquility and Alleviation of Worries and Sorrows.

5. Patience and Seeking Reward: Those who do not believe in al-Qadr might be driven by worry and distress to disbelieve in Allah. Some might go mad, some might be afflicted with wiswas (whispers and doubt), and some might kill themselves. This is why suicide rates are high in countries where people do not believe in al-Qadr, like America, Denmark, and Sweden. Most people afflicted with nervous disorders do not believe in al-Qadr or have weak faith in it.

6. Generosity: A believer in al-Qadr knows they will not become poor unless Allah decrees it, so they give generously without worry.

7. Sincerity: The one who believes in al-Qadr does not perform actions for the sake of people; because they know that people cannot benefit them with anything that Allah has not decreed, and they cannot harm them with anything that Allah has not decreed.

8. Reliance on Allah, Certainty, and Submission to Him: Allah says: “Say, ‘Nothing will befall us except what Allah has decreed for us.’” (Surah al-Tawbah 9:51)

9. Avoiding reliance on soothsayers, astrologers, and charlatans: A believer knows these things cannot bring about any benefit or harm that Allah has not decreed.

10. Contentment and not being overly attached to worldly pleasures.

11. Humility: If Allah elevates a person with wealth, status, knowledge or other matters, they recognize it is from Allah and that He could take it away if He wills, as He is capable of all things.

12. Enraging the innovators who attempt to control Allah’s wisdom and His law [by fabricating and imposing their own interpretations].

Source: al-Jami‘ al-Sahih fil-Qadr (pp. 12-13)