With such a word that less knowledgeable people might think that the one who performs these two rak'ahs in the mosque is sinful, because the Prophet (peace be upon him) has ordered them to be performed in the homes.

Sayyiduna Mahmood bin Labeed رضي الله عنه narrates that the Messenger of Allah صلى الله عليه وسلم came to the tribe of Banu Abd Ash-hal and led them in the Maghrib prayer. Then, when he finished the prayer with salam, he said: "Pray these two rak‘ahs in your homes." (Qatadah) says: Indeed, I saw Sayyiduna Mahmood رضي الله عنه, while he was the imam of his people, he would lead them in the Maghrib prayer. Then he would come out and sit in the courtyard of the mosque, until shortly before ‘Isha, he would get up, go home, and perform these two rak‘ahs.

Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) narrates that the Prophet Muhammad (peace be upon him) offered the Maghrib prayer in the mosque of the tribe of Banu Abd Ash-hal. When he (peace be upon him) had finished the prayer, the people stood up and began to offer the Sunnah prayers, so the Prophet Muhammad (peace be upon him) said: "You should offer this prayer in your homes."