I have a cousin brother who is around 7 to 8 years older than me. He calls me betaa (son in urdu) on some occasion purposely or may be just for fun. I don't like it. I want to know if it's allowed in Islam to call anyone son except to our own child?
as far as I know there is a hadeeth in "muslim" that "anas ibn malek" reported that " Allah's Messenger (ﷺ) addressed me 'O My Son' "
Reference : Sahih Muslim 2151 In-book reference : Book 38, Hadith 38 USC-MSA web (English) reference : Book 25, Hadith 5351
also check this fatwa - but in Arabic -
صحيح مسلم» كتاب الآداب» باب جواز قوله لغير ابنه يا بني واستحبابه للملاطفة
"قال قال لي رسول الله صلى الله عليه وسلم يا بني"
this is not a fatwa (I'm not a scholar or mofty) , but I think according to muslim hadeeth you are allowed to call a kid "son" as some sort of kindness, unless it is considered offensive word in some cultures or you express it in an impolite way