Is Whistling Permissible in Islam?
Shaikh Al-Albānī, may Allāh have mercy on him, said:
Making a whistling sound with the mouth: the answer [to this question] has come before, that it is from the worship of pagans [those who give or attribute to others what belongs to Allāh alone]:
وَمَا كَانَ صَلَاتُهُمۡ عِندَ ٱلۡبَیۡتِ إِلَّا مُكَاۤءࣰ وَتَصۡدِیَةࣰۚ فَذُوقُوا۟ ٱلۡعَذَابَ بِمَا كُنتُمۡ تَكۡفُرُون
Their praying at the Sacred Mosque [of the Kaʿbah] was nothing but whistling and clapping, so taste punishment because of what you have done of disbelief. [Al-Anfāl 35]
Tasjīlāt Mutafirriqah, Tape 298, no. 6, 00:14:20, alalbany.org.