Sunan At-Tirmidhi

Narrated Masruq:""A man came to 'Abdullah and said: 'A story teller has said that a smoke will appear from the earth, taking the hearing of disbelievers and manifesting as a cold for the believers.'"" He became angry, and since he was reclining, he sat up then said: 'When one of you is asked about something he knows, then let him speak accordingly' - Mansur (one of the narrators) narrated it as: ""Then let him inform of it"" - ""And when asked about what he does not know, then let him say: ""Allah knows best."" For indeed, it is part of a man's knowledge, that when he is asked about something he does not know, he says: ""Allah knows best."" For verily Allah, Most High said to His Prophet: Say: ""No wage do I ask of you for this, nor am I one of the pretenders (38:86)."" When the Messenger of Allah (ﷺ) saw that the Quraish were behaving stubbornly with him, he said: ""O Allah! Assist me against them with seven (years of famine) like the seven of Yusuf."" So He punished them with drought making everything barren, until they ate skins and carcasses"" - one of them said: ""bones."" He said: 'And it appeared that smoke was coming out of the earth. So Abu Sufyan came to him and said: ""Verily your people are being destroyed, so supplicate to Allah for them."" He said: ""So this is about His saying: 'The Day when the sky will bring forth a visible smoke, covering the people, this is a painful torment (44:10 & 11).'"" Mansur narrated it as: ""So this is about His saying: Our Lord! Remove the torment from us, really we shall become believers (44:12)."" - ""So shall the punishment be removed from them in the Hereafter? Al-Batshah (humiliated defeat in Badr), Al-Lizam (disbeliever captives from Badr), the smoke,"" - one of them said: ""The moon"" the other said: ""The Romans have all passed