During the time of the Messenger of Allah ﷺ, the mosque was built with mud bricks, its roof made of palm fronds, and its pillars from palm trunks. Abu Bakr did not add anything to it. Umar expanded it and rebuilt it on the same design as it had been during the time of the Messenger of Allah ﷺ, using mud bricks and palm fronds, and he replaced its pillars with new wood. Then Uthman changed it, expanding it considerably. He built its walls with carved stones and gypsum, made its pillars from carved stones, and roofed it with teak wood.
حدثنا يعقوب حدثنا أبي عن صالح حدثنا نافع أن
أن المسجد كان على عهد رسول الله ﷺ مبنيا باللبن وسقفه الجريد وعمده خشب النخل فلم يزد فيه أبو بكر شيئا وزاد فيه عمر وبناه على بنائه في عهد رسول الله ﷺ باللبن والجريد وأعاد عمده خشبا ثم غيره عثمان فزاد فيه زيادة كثيرة وبنى جداره بالحجارة المنقوشة والقصة وجعل عمده من حجارة منقوشة وسقفه بالساج
Its isnad is sahih. Bukhari related it in volume 1:449-450, and Abu Dawud in volume 1:171-172, both through Yaqub bin Ibrahim bin Saad, with this same isnad. Munziri, in entry 424, forgot to attribute it to Bukhari, which gives the false impression that Abu Dawud was alone in transmitting it among the Six Books.Al-labin, with fatha on the lam and kasra on the ba, means unbaked bricks. Al-amad, with two dammas, is the plural of amud (pillar/post), and with two fathas it is a collective noun, and both forms are attested in the transmission of this hadith. Al-khashab, with two dammas and with two fathas, is the plural of khashabah (piece of wood), and both forms are attested here as well.Al-qissah, with fatha on the qaf and a doubled, open sad, means gypsum plaster, in the language of the people of Hijaz, and Abu Dawud said the same in the Sunan. Khattabi said it is something resembling gypsum plaster, but is not actually it.Regarding "wa saqfahu," Qastallani said in his commentary on Bukhari, volume 1:359-360, that it is with fatha on the qaf and the fa, connected to "jamal" (camel/beam), while in the Yunini branch it appears as "wa saqfahu" with a silent qaf, connected to "amadahu" (its pillars). Ramawi vocalized it as "wa saqqafahu," with a doubled qaf.Al-saj, with sin and jim, is a type of tree brought from Hind, its singular being sajah.As for the phrase "mabniyyan bil-labin" (built with unbaked bricks), one manuscript in the margin of K adds "wal-teen" (and clay). And regarding the description of what Umar did, "wa aada amadahu khashaban" (he restored its pillars with wood), in K it reads "fa-aada," which is a variant found in the margin of M.