Worship only Allah alone without associating any partner with Him ; Respect your elders including your parents ; Be truthful at all times .

The Prophet Muhammad ﷺ warned against four major sins that are considered to be the worst of all sins. These include associating partners with Allah, which is known as shirk in Islam; murder; being undutiful to one's parents; and giving false witness or making a false statement. Shirk is considered the most serious sin in Islam because it involves attributing something or someone else as equal to God Almighty, which goes against the core belief of monotheism in Islam. Murder is also a grave sin because it involves taking away someone’s life without any justification or permission from God Almighty. Being disrespectful towards one’s parents is also considered a major sin because it goes against Islamic teachings that emphasize respect for elders and those who have authority over us such as our parents and teachers. Lastly, giving false witness or making a false statement is also prohibited in Islam since it involves lying which goes against Islamic teachings that emphasize truthfulness and honesty at all times.