Is repeating part of a song that includes supplication to other than Allah, such as "Ya Tahira" (O Pure One), considered disbelief (kufr) or polytheism (shirk), especially if one stops before completing it upon realizing that supplicating other than Allah is shirk?

Repeating words unintentionally is a mistake, but it does not reach the level of disbelief (kufr). One must repent from being uncertain about what is being said, and a believer does not speak about what he does not understand. It is advisable to supplicate and show humility, disregard obsessive thoughts (waswas), and consult a psychiatrist.