The ruling on gratitude as an act of worship and the distinction between thanking Allah and thanking a person

Question:
He says: Honorable Shaykh, may Allah grant you success, is gratitude an act of worship? And if I say, "I thank Allah and I thank so-and-so," or "I thank Allah, then I thank so-and-so," is that permissible?

Answer:
Gratitude is an act of worship. Do not say, "I thank Allah and I thank so-and-so," using the conjunction "and"; that is not permissible. Say, "I thank Allah, then I thank so-and-so," or "I thank Allah, then I thank you." The word "then" establishes the rank of thanking the person as following the thanks to Allah, and it is subordinate to the thanks to Allah, Glorified and Exalted is He.