Is it permissible to thank a driver with "Jazakallahu Khairan" (May Allah reward you with goodness) after every service he performs, or is that considered submission through speech?

It is permissible for a woman to thank the driver if there is no fear of temptation (fitnah), and if her voice is free from softness, breaking, or excessive mellowness; based on the statement of Al-Hafiz: "Chapter on men greeting women and women greeting men... The meaning of its permissibility is when there is no fear of temptation," and based on the statement of Ibn Al-Arabi in his interpretation of the verse: {then do not be soft in speech, lest he in whose heart is disease should covet} (Al-Ahzab: 32): "Allah Almighty commanded them that their speech should be firm, and their words decisive, and not in a manner that creates a relationship in the heart through the apparent softness that would make the listener covetous."