It is incumbent on those who are present [in a religious meeting (or conference)] to convey the knowledge to those who are absent

Narrated Sa`id:

Abu Shuraih said, "When `Amr bin Sa`id was sending the troops to Mecca (to fight `Abdullah bin Az- Zubair) I said to him, 'O chief! Allow me to tell you what the Prophet (ﷺ) said on the day following the conquests of Mecca. My ears heard and my heart comprehended, and I saw him with my own eyes, when he said it. He glorified and praised Allah and then said, "Allah and not the people has made Mecca a sanctuary. So anybody who has belief in Allah and the Last Day (i.e. a Muslim) should neither shed blood in it nor cut down its trees. If anybody argues that fighting is allowed in Mecca as Allah's Messenger (ﷺ) did fight (in Mecca), tell him that Allah gave permission to His Apostle, but He did not give it to you. The Prophet (ﷺ) added: Allah allowed me only for a few hours on that day (of the conquest) and today (now) its sanctity is the same (valid) as it was before. So it is incumbent upon those who are present to convey it (this information) to those who are absent." Abu- Shuraih was asked, "What did `Amr reply?" He said `Amr said, "O Abu Shuraih! I know better than you (in this respect). Mecca does not give protection to one who disobeys (Allah) or runs after committing murder, or theft (and takes refuge in Mecca).