Praise be to Allah.
One aspect of the etiquette which Islam pays attention to with regard to gatherings is that two people should not speak privately to the exclusion of the third, and that is so as to avid upsetting anyone.
Al-Bukhaari (6290) and Muslim (2184) narrated that ‘Abdullah ibn Mas‘ood (may Allah be pleased with him) said: The Prophet (blessings and peace of Allah be upon him) said: “If you are three, two should not converse privately to the exclusion of the other one until you join some other people, so that you do not make him sad.”
At-Tirmidhi (2825) narrated that ‘Abdullah ibn Mas‘ood said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “If you are three, two should not converse privately to the exclusion of their companion.” Classed as saheeh by Shaykh al-Albaani in Saheeh Sunan at-Tirmidhi.
The apparent meaning of the prohibition mentioned in the hadiths quoted above indicates that it is haraam. Therefore it is haraam for two to converse to the exclusion of the third, or for a group of people to converse to the exclusion of one of them.
An-Nawawi (may Allah have mercy on him) said: These hadiths indicate that it is prohibited for two people to converse privately in the presence of a third, and for three or more to do so in the presence of one. This prohibition indicates that it is haraam; therefore it is haraam for a group to converse privately to the exclusion of one of them, unless he gives them permission to do that."( Sharh Muslim by an-Nawawi)
There are some cases in which an exception is made from the prohibition on conversing privately that is mentioned in the hadiths:
1.. The first case is when two converse privately with the permission of the third; so if he gives them permission, it is permissible, because of the reports narrated by Ahmad (6302) from Ibn ‘Umar (may Allah be pleased with him), who said:
The Messenger of Allah (blessings and peace of Allah be upon him) said: “If you are three, two should not converse privately to the exclusion of the third, except with his permission, for that will make him sad.”
2.. The second case is when the number is more than three, in which case it is permissible for two to converse privately to the exclusion of the others, because of the report narrated by Abu Dawood (4581), in which it says: Abu Saalih said: I said to Ibn ‘Umar: (What if they are) four? He said: Then it does not matter.
An-Nawawi (may Allah have mercy on him) said in Sharh Muslim: If they are four, and two of them converse privately to the exclusion of the other two, then there is nothing wrong with that, according to scholarly consensus. End quote.
Shaykh Muhammad ibn ‘Abd al-Haadi as-Sindi (may Allah have mercy on him) said: The words “ If you are three” indicate that it is permissible [for two people to converse privately] if there are more than three people, because it may be that the third person will be comforted by the presence of the fourth and, moreover, with the presence of the fourth person, the third person will not fear any harm to himself from the other two."(Haashiyat as-Sindi ‘ala Sunan Ibn Maajah)
2.. The third case is when there is a need or interest that outweighs any negative consequences of the private conversation. In that case, it is permissible for two to converse to the exclusion of the third.
An-Nawawi (may Allah have mercy on him) said in Riyadh as-Saaliheen: Chapter on the prohibition on two conversing privately to the exclusion of the third without his permission except in the case of necessity.
Shaykh Muhammad Saalih al-Munajjid (may Allah preserve him) said, discussing one of the forms of private conversation that are permissible:
Another of these forms is when, you sometimes have a guest who has come to visit you, and whilst you are talking to him, your child or your servant comes to you, and you have no choice but to whisper into the ear of the child or servant, telling them to prepare food, for example, or to clear the way. Or sometimes your child may say to you: My mother is saying such and such. In this case, politeness dictates that such things should not be said out loud in front of the guests. This case is an interest that outweighs any possible negative outcomes, because the guest will understand that when you whisper to this child of yours, you are not going to say anything bad about him; rather you and he are organizing something that has to do with offering hospitality, or has to do with some family matter, so he will not feel upset at all. These are some examples of the type of private conversation that is permitted.
End quote from the tape: Kayfa takoou Majaalisuna Islamiyyah.
And Allah knows best.