Is it permissible to say "ah, ah" or "yai, yai" to express pain, and what is incumbent upon someone who says "yai, yai" when they fall?

A patient's utterance of "Ah" or similar expressions to convey pain is permissible without dislike, provided it doesn't involve excessive resentment or despair. This is because the inability to endure excessive pain is a natural human inclination. Such expressions of pain have been reported from Companions like Abu Bakr and Aisha, and even from Prophet Ayyub (Job), peace be upon him. Some scholars disliked moaning and complaining by way of reporting, but others, like Imam Al-Nawawi and Al-Hafiz Ibn Hajar, refuted this, considering only that which is expressly prohibited to be disliked. The Prophet's (peace be upon him) statement to Aisha, "Nay, rather it is I, O Aisha, my head!" could be interpreted as consolation or simply an acknowledgment of pain without complaint. In summary, moaning is permissible, but refraining from it and engaging in remembrance of Allah is more virtuous. As for the word "Yai" when falling or colliding, it usually (unintentionally) indicates a form of panic, so no legal ruling applies to it, or it is intended to draw attention, in which case there is no harm in it.