What is the ruling on someone who finds it difficult to pronounce the letter "seen" (س) such that it comes out similar to "saad" (ص)?

If a person is unable to pronounce the letter 'seen' (س) and instead pronounces it as 'saad' (ص) despite trying and training, there is no sin upon him, as Allah Almighty says: "Allah does not burden a soul beyond its capacity." However, if he is able to learn, then he must do so, and he sins by neglecting to learn. He must also make up every prayer he performed during the period of his negligence in learning, as stated in Al-Majmoo' by Al-Nawawi. One should be cautious of excessive scrupulosity (waswasah) regarding the articulation points and characteristics of letters.