When the low feeling has no event behind it
Sadness is named in the Qur'an, and it is spoken to directly. God tells the Prophet "we know well that what they say grieves you" — an observation set down before any comfort follows it. The feeling is treated as real enough to be addressed by name.
The phrase that recurs is "do not grieve", and it almost never travels alone. Maryam hears it in labour, alone and frightened, and the next thing she is told is that "your Lord has placed a stream beneath you". Yusuf says it to his brother while the wrong is still going on around them. Something practical is usually set down beside the instruction.
Sadness is wider than grief and lighter than despair, which is why it has its own page here. Grief attaches to a loss you can point to, and those verses are gathered at verses about grief. What the Qur'an calls huzn reaches further than that: the flat afternoon, the ache after a conversation, the low mood that arrives with no event behind it. If the heaviness has stopped lifting at all, verses about depression sits closer to where you are.
The prophets in these passages are sad, and the text records it without embarrassment. Ya'qub says outright that parting from his son saddens him, years before the loss that turns his eyes white. Musa comes back from the mountain angry and grieved. Their sadness sits inside the story as ordinary weather, with nothing to suggest that stronger faith would have kept it away.
The last word given to sadness here is in the past tense. The people who arrive say "who has taken all sorrow away from us", and the recurring promise that there will be no fear and no grief is set in a future rather than demanded of you this afternoon. That leaves room to be sad today and still be held. How we read passages like these is set out in our principles.