Destiny, sometimes referred to as fate (from Latin fatum – destiny), is a predetermined course of events. It may be conceived as a predetermined future, whether in general or of an individual.
This narration from Ameerul Mo'mineen is mentioned in Nahjul- Balaghah, wisdom number 284. Ameerul Mo'mineen was asked about Al-Qadar, not Al-Qadr, he replied: A dark path so don't tread upon it and a deep sea so don't enter inside it, and secret of Allah, so don't take the trouble of indulging in it.
'This "Qadar" is not al-Qadr which is called in English as destiny. Qadar in this statement is above the limits of our thinking and our ability of understanding. It is the secret of Allah which we can not understand . We as human beings have limits in all our abilities and qualities which can not be exceeded. We can see up to certain distance not more and we can hear up to certain waves no more and we can think upto certain limits and no more. Trying to think about things out of our limits will land us in trouble and suffering. That is why Ameerul Mo'mineen replied the above reply which concerns secret of Allah, not simple destiny.
It is really difficult for us human beings to know what aspects of fate are unchangeable and which are changeable as this knowledge belongs to Allah. However, hadith say that some unwanted things which are fated can be changed by prayer (du'a) or good acts (such as charity). God knows best.
Here are some thoughts on that: https://www.al-islam.org/ask/can-dua-change-your-taqdeer-and-fate
Committing suicide is a major sin in Islam because it comes as a result of losing hope in the mercy of Allah which is itself a major sin, and it is a crime of killing which is another major sin. Nevertheless, those who die during committing major sins, remain Muslims and we must perform on their dead bodies all rituals which must perform on any Muslim who dies e.g. Ghusl of the dead body, Kafan and burial in Muslim grave yard.
Allah (SWT) knows what is their hearts and He deals with them. We pray for all the believers to get the Mercy of Allah (SWT).
Allah says in the Quran that no one will bear the burden of another. We are all responsible for our deeds.
It is not healthy to go through life with a sense of pre-destination that one will go to hell, because that can easily become a self-fulfilling prophecy.
Sometimes some people are irresponsible when they talk about illegitimate children and either say things without thinking, or else they don't critically examine the texts they are talking about and quote them without thinking or comparing or examining them closely. It perhaps doesn't occur to them that some of the people sitting there listening are not of legitimate birth. There should be more responsibility in discussing these things so that people do not go around worrying they will go to hell because of what their forebears did.
In Usul al-Kafi Vol. 1 (available from WOFIS in Iran), Imam 'Ali (as) explains that the decree is not finalised until the actual moment that it is brought into existence. Up until that time, there is room for the decree to be changed, or withheld. It is a key teaching from the Ahl al-Bayt (as) that you can have a living and dynamic relationship with Allah (swt) and that du'a, as well as other actions, can alter what is decreed. I know of the expression in the Middle East where they say 'the name of your spouse is written on your forehead', which sounds like an unchangeable destiny, but through du'a you may change that name.
Yes. Du'a can change many things in our life and make it much better. Du'a can make you marry a better person and can make your life happier. Many destined things can be changed by Du'a and good deeds or can be worsened by bad deeds.
Tablet of Destiny اللوح المحفوظ (Al-Lawh Al-Mahfoodh) has what Allah The Glorious Has written for us which is unchangeable like our parents, relatives, tribe, place of birth, color of eyes and skin etc.
Such matters in our life are fixed in the Tablet of Destiny (Al-Lawh Al-Mahfoodh) but it does not make any change nor effect on us on the Day of Judgment.
Our life span, our income, our health can be changed according to our deeds, as all are in the (Tablet of Mahw and Ithbaat) (omitting or confirming). This tablet is not Al-Lawh Al-Mahfoodh which is unchangeable.