Saying · Monday, 26 Safar
If you imprison him, his words will still reach his followers. And if you send him into exile, you will only be sending him back to his followers: it will strengthen them.
Monday, 26 Safar, 13th year of the dawah / 1st year of the Hijrah · 1 BH
Details differ across the sources
The identification of the old man from Najd as Iblis rests on a weak narration.
The Quraysh held a secret night meeting at Dar al-Nadwa, with representatives from every tribe except Banu Hashim, even Abu Lahab was excluded, since the plot targeted his own nephew, and Mut'im ibn Adi was excluded as the Prophet ﷺ's protector. In a weakly-narrated report, an uninvited old man claiming to be from Najd asked to join and offered counsel; Ibn Abbas said this old man was Iblis. Suggestions to imprison or exile the Prophet ﷺ were raised and rejected before Abu Jahal proposed having every tribe send one man to strike him together, so his blood would be on all their swords and no single tribe could be blamed or fought in revenge. Jibril AS then came to the Prophet ﷺ and told him he must make Hijrah immediately; the Prophet ﷺ spoke to Abu Bakr RA that same evening and left that same night.
Ibn Abbas reported that Qur'an 8:30 was revealed regarding this very plot.
Other events recorded in 1 BH. Their order within the year is not established; use the storyline above for the sequence.
If you imprison him, his words will still reach his followers. And if you send him into exile, you will only be sending him back to his followers: it will strengthen them.
You still haven't said the main point which everyone is thinking but no one has the guts to say: let us just kill him. We will do it in a way that nobody can get angry at any one tribe: let every single tribe send one representative, so that his blood is on everyone's swords and no one knows who killed him. Then the Banu Hashim cannot wage war against all of us, and will have to accept the blood money.
Spoken at the Quraysh's secret council at Dar al-Nadwa after their suggestions to imprison or exile the Prophet ﷺ had already been rejected.
This is the right decision!
وَإِذْ يَمْكُرُ بِكَ الَّذِينَ كَفَرُوا لِيُثْبِتُوكَ أَوْ يَقْتُلُوكَ أَوْ يُخْرِجُوكَ ۚ وَيَمْكُرُونَ وَيَمْكُرُ اللَّهُ ۖ وَاللَّهُ خَيْرُ الْمَاكِرِينَ
“And [remember, O Muhammad], when those who disbelieved plotted against you to restrain you or kill you or evict you [from Makkah]. But they plan, and Allah plans. And Allah is the best of planners”
Ibn Abbas reported this ayah was revealed regarding the Quraysh's plot to imprison, exile, or kill the Prophet ﷺ.
وَإِن كَادُوا لَيَسْتَفِزُّونَكَ مِنَ الْأَرْضِ لِيُخْرِجُوكَ مِنْهَا ۖ وَإِذًا لَّا يَلْبَثُونَ خِلَافَكَ إِلَّا قَلِيلًا
“They tried their best and they almost succeeded in getting rid of you from the land, but if they were to succeed, then they themselves would only last for a short while (before Allah destroys them).”
A Makki verse ("they tried to drive you out of the land") standardly tied to the Quraysh's plot to kill/expel the Prophet ﷺ at Dar al-Nadwa on the eve of the Hijrah -- not to Tabuk, a theory the DB's own battle-of-tabuk event explicitly rejects.