According to Islamic teachings, God Himself claims that it is HE who bestows happiness and sadness:
“IT IS HE WHO MAKES YOU LAUGH AND CRY” (QURAN)But still that immense sadness of Prophets and Messengers (PBUT) didn’t stop them from pursuing their missions even more vigorously. Their sadness didn’t result in hopelessness nor in a state of inaction-in other words, they went through periods of sadness but not depression. Depression on the other hand, is characterized by hopelessness, loss of meaning in life, self-worthlessness and feeling of sadness without being able to identify the cause of the gloominess in life.