Almost all scholars say there were 124,000 prophets sent by Allah. Where does this number come from and what is the evidence to support it?
This number comes from a long hadith in Musnad Imam Ahmad, narrated by Abu Umamah al-Bahili relating a conversation that Abu Dharr (ra) had with the Prophet (saws). This is some text from toward the end of that hadith:
قُلْتُ يَا رَسُولَ اللَّهِ كَمْ وَفَّى عِدَّةُ الْأَنْبِيَاءِ قَالَ مِائَةُ أَلْفٍ وَأَرْبَعَةٌ وَعِشْرُونَ أَلْفًا الرُّسُلُ مِنْ ذَلِكَ ثَلَاثُ مِائَةٍ وَخَمْسَةَ عَشَرَ جَمًّا غَفِيرًا.
To translate roughly, this says
I said "O Messenger of Allah, how many Prophets were there?" He replied "One hundred twenty four thousand, from which three hundred fifteen were jamma ghafeera."
(I don't know how to translate the last phrase)
To see the full hadith, scroll down to number 21257 on this page.
I do not know for sure the authenticity or grade of this hadith, so take it with a grain of salt until someone comes up with that information. I do remember that the chain of narration that includes the numbers includes a narrator who is not considered trustworthy.
Update: It appears as if all narrations of these numbers in Musnad Ahmad, ibn Hibban, ibn Hatim etc. are all declared weak by the scholars of hadith. Check here for a discussion in Arabic, and also here (h/t @SystemDown)
In one Hadith, it's said that there were 124 prophets which is a quite popular one.(1)
In another, it's said there were 124,000 prophets and 313 messengers.(2)
And yet in another one, it's said that they were 124,000 where five of them had Holy book. (3)
It's said in Tafsir nemone that it can be concluded that there's not a single news -as said in Tafsir Ruh-al-bayan- however many of Ahadith and news emphasize that there were 124,000 prophets.(4)
In Qur'an the names of 26 prophets has been mentioned explicitly:
Adam, Nooh, Edris, Saleh, Hood, Ismaeil, Ishagh, Yoosof, Loot, Ya'ghoob, Moosa, Haroon, Sho'aib, Zakarya, Yahya, Isa, Davoud, Solayman, Elyas, Elyas', Zo-al-kafl, Ayoob, Yoonos, Aziz and Muhammad (PBUT).
There are other prophets who has been mentioned implicitly but their names hasn't been mentioned explicitly, like "Eshmooil" which has been mentioned in Ayah 248 of Surah Baghareh as «وَقَالَ لَهُمْ نَبِیُّهُمْ» and "Yoosha'" in Ayah 60 of Surah Kahf as «وَإِذْ قَالَ مُوسَی لِفَتَاهُ».
(1) Majma-al-bayan, under Ayah 78 from Surah Al-ghafer, in another hadith it's said 8,000 which doesn't contradict the 124,000 assumption since it could be about more important prophets.
(2) Behar-al-anvar, number 11, page 31
(3) Ibid, page 41
(4) Tafsir Nemone, number 20, page 184
(5) Ibid, page 185
Anyone sent by Allah swt is a Messenger (total = 144000) see Quran 36:14 اذ ارسلنا اليهم اثنين فكذبوهما فعززنا بثالث فقالوا انا اليكم مرسلون.
Some Messengers are chosen as Prophets and are given Book and Wisdom (total 313) see Quran 3:81. واذ اخذ الله ميثق النبين لما ءاتيتكم من كتب وحكمه ثم جاءكم رسول مصدق لما معكم لتومنن به ولتنصرنه قال ءاقررتم واخذتم علي ذلكم اصري قالوا اقررنا قال فاشهدوا وانا معكم من الشهدين
The Messenger in 3:81 will come after all of them and they must believe in him and support him. My current belief is that that Messenger is Imam Al-Mahdi (as) and only the Prophets who were raised by Allah or killed/poisoned will return to pray behind Imam Al-Zamaan (as) including our own Prophet Muhammed (pbuh+f) who is the 313th and last Prophet but not last Messenger.
Allah swt calls him in Quran 7:157 "Al-Rasool Al-Nabi" not vise versa. ٧_١٥٧ الذين يتبعون الرسول النبي الامي الذي يجدونه مكتوبا عندهم في التوريه والانجيل يامرهم بالمعروف وينهيهم عن المنكر ويحل لهم الطيبت ويحرم عليهم الخبيث ويضع عنهم اصرهم والاغلل التي كانت عليهم فالذين ءامنوا به وعزروه ونصروه واتبعوا النور الذي انزل معه اوليك هم المفلحون
Rasool = Messenger Nabi = Prophet Rasool Nabi = Prophet Messenger (in English adjective comes before noun unlike Arabic).
Finally why 144000 Messengers not 124000 because 144000 - 313 = prime (وتر) and 313 is prime too. See Quran 89:3 والشفع والوتر
Please see why والشفع والوتر are Composites and Primes according to surat Al-Fatiha and NOT Evens and Odds at www.heliwave.com/Primalogy.pdf