Thawr bin Zayd Deeli reported,

A man would divorce his wife and then take her back, though he had no need of her and no desire to keep her, simply so that her waiting period would be drawn out and she would be harmed by it. So Allah revealed "and do not hold on to them in order to harm them, transgressing the limits. Whoever does that has wronged himself" [Baqarah 2:231]. By this Allah was admonishing them.

و حدثني عن مالك

عن ثور بن زيد الديلي

أن الرجل كان يطلق امرأته ثم يراجعها ولا حاجة له بها ولا يريد إمساكها كيما يطول بذلك عليها العدة ليضارها فأنزل الله تبارك وتعالى {ولا تمسكوهن ضرارا لتعتدوا ومن يفعل ذلك فقد ظلم نفسه} يعظهم الله بذلك