The best medicine
Definition 1 of 1
Pro Tip 1/3Figurative Meaning
Understand that it's not literal medicine but suggests something beneficial for health or mood. 
During tough times, listening to music became the best medicine for him.
Pro Tip 2/3Positive Connotation
Recognize its positive emotional implications, usually signaling joy or comfort. 
Her kind words were the best medicine after a hard day.
Pro Tip 3/3Idiomatic Usage
It's an idiom, so don't change the words. 'The finest medicine' has a different meaning. 
After the reunion, I realized that friendship is truly the best medicine.