The Prophet ﷺ said, "If you say to your companion 'Be quiet' on Friday while the imam is delivering the sermon, you have spoken idly."Sufyan said that Abu Zinad remarked, "This is the dialect of Abu Hurairah."
قال قرئ على سفيان سمعت أبا الزناد يحدث عن الأعرج
عن النبي ﷺ إذا قلت لصاحبك يوم الجمعة والإمام يخطب أنصت فقد لغيت قال سفيان قال أبو الزناد هي لغة أبي هريرة
Its isnad is sahih. Muslim narrated it 1:233, from Ibn Umar, from Sufyan, with this same isnad. Malik narrated it in the Muwatta 103, from Abu Zinad. Bukhari narrated it 2:343, and Muslim, through another route, from Abu Hurairah. In Muntaqa 1624 it states that the whole group narrated it except Ibn Majah. See what has already appeared in Musnad Ali 719, in Musnad Ibn Abbas 2033, and in Musnad Abdullah bin Amr 6701, 7002.His saying "laghayta", both of them vocalized it with fatha on the dotted ghayn, which is the better reading in our view. It was vocalized in the Astana edition of Sahih Muslim 3:5 with kasra on it, following the apparent sense of Nawawi's statement in his commentary 6:138. The linguists said, "It is said 'lagha yalghu' like 'ghaza yaghzu', and it is also said 'laghiya yalgha' like 'amiya yama', two dialects, the first being more eloquent." The apparent sense of the Quran requires this second form, which is the dialect of Abu Hurairah. Allah the Exalted said, "And those who disbelieve say, 'Do not listen to this Quran and drown it out with noise, so that perhaps you may overcome'" [Fussilat 41:26]. So this follows the form laghiya. Had it been from the first form, he would have said "walghu" with damma on the ghayn. But it is vocalized, in a sound manuscript of Sahih Muslim in my possession, with fatha on the ghayn. This is what appears from the explanation of the reading, as we shall mention.As for the linguists, in Lisan al-Arab it says, "lagha fi al-qawl yalghu, wa yalgha, laghwan, wa laghiya, with kasra, yalgha, lagha, wa malghatan," meaning he erred and spoke falsehood. In Qamus [al-Muhit] it says, "laghiya fi qawlihi", like "saa", "daa", and "radiya".As for the explanation of the reading, the best of what Abu Hayan quoted in Bahr [Muhit] 7:494 is that Akhfash said, "It is said 'lagha yalgha' with fatha on the ghayn, and its expected analogical form would be damma, but it was given fatha because of the guttural letter." So the first reading is from "yalgha", and the second is from "yalghu".