[JulietOreira]

Many references are given on this page:
http://www.askimam.org/fatwa/fatwa.p...2adf5bac07650f

Thanks for the link, akhi. Some of the ahadith quoted in the answer are worth copying here:

“Ali (radiyallaahu anhu) reports that Rasulullah (sallallaahu alayhi wa sallam) used to perform four rakaats salaah before and after the jummah salaah”
(Al-Awsat of Tabrani / Nasb Al-Rayah, vol 2, pg 206, Ilmiyya /I’laus Al-Sunan, vol 7, pg 13, Idaratul Al-Quran)
The chain of narrators in the above narration is sound. (Tarhut Al-Tathreeb, vol 3, pg 36, Ilmiyya)

“Abdullah Bin Umar(radiyallaahu anhu) reports that Rasulullah (sallallaahu alayhi wa sallam) used to perform four rakats of salat before the jummu’ah salat and would not separate them with a salaam; then he would perform two rakats of salat after jummu’ah followed with another four rakats of salat”
(Sharh Ma’ani Al-Aathaar, vol 1, pg 233, Haqqaniyya)
The chain of narrators in the above Hadith is sound (Aathaar Al-Sunan, pg 302, Imdadiyya)

“Abdullah (bin Mas’ood) reports that Rasulullah (sallallaahu alayhi wa sallam) used to perform four rakaats before the jummah salaah”
(Musannaf Ibn Abi Shayba, vol 4, pg 114, Al-Majlis al-Ilmi)

“Abu Hurairah (radiyallaahu anhu) reports that Rasulullah (sallallaahu alayhi wa sallam) said: Whoever intends to perform salat, then he should perform four rakats salat before the jummu’ah salat and four rakats after jummu’ah salat”.
(Sharh Mushkil Al-Aathaar,#4108, vol 10, pg 298, Muassasah Al-Risalah)

"Abu 'Abdir Rahman Al-Sulami reports: “Abdullah (bin Mas’ood) used to command us to perform four rakaats salaah before the jummah salat and four rakats salat after the jummah salaah”. (Musannaf Abdir Al-Razaaq, vol 3, pg 247, Idaratul Quran)
The chain of narrators in the above Hadith is authentic. (Athaar Al-Sunan, pg 303, Imdaadiyya)