Sahih Al Bukhari (46)

حَدَّثنا إِسْمَاعِيلُ، قَالَ: حَدَّثَنِي مَالِكُ بْنُ أَنَسٍ، عَنْ عَمِّهِ أَبِي سُهَيْلِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، أَنَّهُ سَمِعَ طَلْحَةَ بْنَ عُبَيْدِ اللهِ يَقُولُ: جَاءَ رَجُلٌ إِلَى رَسُولِ اللهِ صَلى الله عَلَيهِ وسَلمَ مِنْ أَهْلِ نَجْدٍ، ثَائِرَُ الرَّأْسِ، يُسْمَعُ دَوِيُّ صَوْتِهِ، وَلاَ يُفْقَهُ مَا يَقُولُ، حَتَّى دَنَا، فَإِذَا هُوَ يَسْأَلُ عَنِ الإِسْلاَمِ، فَقَالَ رَسُولُ اللهِ صَلى الله عَلَيهِ وسَلمَ: خَمْسُ صَلَوَاتٍ فِي اليَوْمِ وَاللَّيْلَةِ، فَقَالَ: هَلْ عَلَيَّ غَيْرُهَا؟ قَالَ: لاَ، إِلاَّ أَنْ تَطَوَّعَ، قَالَ رَسُولُ اللهِ صَلى الله عَلَيهِ وسَلمَ: وَصِيَامُ رَمَضَانَ، قَالَ: هَلْ عَلَيَّ غَيْرُهُ؟ قَالَ: لاَ، إِلاَّ أَنْ تَطَوَّعَ، قَالَ: وَذَكَرَ لَهُ رَسُولُ اللهِ صَلى الله عَلَيهِ وسَلمَ الزَّكَاةَ، قَالَ: هَلْ عَلَيَّ غَيْرُهَا؟ قَالَ: لاَ، إِلاَّ أَنْ تَطَوَّعَ، قَالَ: فَأَدْبَرَ الرَّجُلُ وَهُوَ يَقُولُ: وَاللهِ لاَ أَزِيدُ عَلَى هَذَا، وَلاَ أَنْقُصُ، قَالَ رَسُولُ اللهِ صَلى الله عَلَيهِ وسَلمَ: أَفْلَحَ إِنْ صَدَقَ.

Talhah ibn `Ubaydullah (may Allah be pleased with him) narrated that a man from Najd with unkempt hair came to Allah's Messenger (peace be upon him) and we heard his loud voice but could not understand what he was saying till he came near and then we came to know that he was asking about Islam. Allah's Messenger (peace be upon him) said: "You have to offer Salah perfectly five times in a day and night (24 hours)." The man asked: "Is there any more (Salah)?" Allah's Messenger (peace be upon him) replied: "No, but if you want to offer the voluntary Salah (you can)." Allah's Messenger (peace be upon him) further said to him: "You have to observe fasting during the month of Ramadan." The man asked: "Is there any more fasting?" Allah's Messenger (peace be upon him) replied: "No, but if you want to observe the voluntary fasting (you can.)" Then Allah's Messenger (peace be upon him) further said to him: "You have to pay Zakah (obligatory charity)." The man asked: "Is there any thing other than Zakah for me to pay?" Allah's Messenger (peace be upon him) replied: "No, unless you want to give alms of your own." And then that man retreated saying: "By Allah! I will neither do less nor more than this." Allah's Messenger (peace be upon him) said: "If what he said is true, then he will be successful (i.e. he will be granted Paradise)."