Muslim

Hadith Commentary: Hafiz Sahib states that when the mention of bad omens came before the Noble Messenger sallallahu alayhi wa sallam, he said: "If any of you sees something he dislikes, let him say:
اللَّهُمَّ لا يَأتي بالحَسَناتِ إلا أنتَ، وَلا يَدْفَعُ السَّيِّئاتِ إلا أنْتَ، وَلا حوْلَ وَلا قُوَّةَ إلا بِكَ (Fath)
That is, if any of you sees something detestable, he should say: O Allah! None brings about good except You, and none repels evil except You. There is no power to avoid sin nor strength to do good except through You, O Allah! You alone are the source of all strength and ability."

Hadith Commentary:
(1)
Evil omens (bad luck) have been declared baseless because they create ill thoughts about Allah and undermine trust in Allah’s decree. Good omens, on the other hand, generate good expectations about Allah, which a believer has been commanded to have. Thus, when the Messenger of Allah (sallallahu alayhi wa sallam) would go out for some need, he liked to hear words such as “Ya Rashid” (O rightly guided one) and “Ya Najeeh” (O successful one).
(Jami‘ at-Tirmidhi, Kitab as-Siyar, Hadith: 1616) (2)
Similarly, when a sick person hears words of safety and health, he becomes happy. Likewise, if someone going to battle meets a person on the way whose name is Fath Khan (Victory), then a good omen can be taken from this that victory will be ours in this battle.
Allah, by nature, has placed love for good things in the human heart, just as seeing something good brings happiness and seeing clear water brings delight, even if one does not have the strength to drink or use it.
(3)
In any case, the only permissible omen is that, without intention or purpose, if a good word happens to reach one’s ears, a person, upon hearing it, should attach good hope to Allah.
And Allah knows best.

Hadith Commentary:
To hear any word of goodness from which some good can be intended—this is a good omen (fa’l), which is not prohibited.

Hadith Commentary:
The Shariah has absolutely negated contagious diseases, even though medical professionals do not accept this; rather, they rationalize it in various ways, saying that illness spreads through germs. However, they also admit that the effect of germs only occurs when the immune system in the body becomes weak. Thus, the real cause is not the existence of germs, but rather the weakness of the body's defense system.
These individuals are grasping the ear from the opposite side.
Silently accept the reality conveyed by the Messenger of Allah (sallallahu alayhi wa sallam) and give it a place in your heart.
Therein lies well-being.
And Allah is the One whose help is sought.

Explanation:
1:
Contagion, that is, a disease does not become infectious by itself; rather, all of this occurs by the command of Allah and according to the destiny He has decreed. However, in order to protect oneself from illnesses, it is recommended (mustahabb) to adopt the means while placing trust (tawakkul) in Allah.

Benefits and Issues:
A good omen, as when the Prophet (sallallahu alayhi wa sallam) said on the occasion of the Treaty of Hudaybiyyah, upon the arrival of Suhayl ibn Amr, the representative of the people of Makkah: "Now your matter has become easy (sahl)."
(Sahih al-Bukhari, al-Shurut, Hadith 2731-2732)

Benefits and Issues:

➊
When the Arabs would set out to do something, on the way they would throw a pebble at a bird or a deer sitting by, and observe which direction it would go.
If it went to the right, they would say the task will be accomplished.
If it went to the left, they would say this task will not be accomplished,
or its outcome will not be good,
and they would return without carrying out the task.

➋
Taking omens in this manner is prohibited in the Shariah.

➌
Placing a finger on numbers or letters, having a parrot draw an omen, and all such various methods of taking omens are all prohibited.

➍
The only permissible omen is that, without intention, if a good word reaches one’s ear and a person, because of it, hopes that Allah will grant him success in his objective.
In this, the listener’s intention or will has no role.