Talhah ibn ‘Ubayd reported: A man came to the Mesenger of Allah, peace and blessings be upon him, from the people of Najd. His hair was unkempt and his loud voice was heard, which could not be understood until he came closer. He was asking about Islam. The Prophet said, “There are five prayers in a day and night.” The man said, “Is there anything else I must do?” The Prophet said, “No, unless you do so voluntarily.” The Prophet said, “And fasting the month of Ramadan.” The man said, “Is there anything else I must do?” The Prophet said, “No, unless you do so voluntarily.” The Prophet mentioned Zakat and the man said, “Is there anything else I must do?” The Prophet said, “No, unless you do so voluntarily.” The man turned back and he was saying, “By Allah, I will never add to this or lessen it.” The Prophet said, “He has succeeded if he is truthful.”
Source: Ṣaḥīḥ al-Bukhārī 46, Ṣaḥīḥ Muslim 11
Grade: Muttafaqun Alayhi (authenticity agreed upon) according to Al-Bukhari and Muslim
عَنْ طَلْحَة بْن عُبَيْدِ اللَّهِ قَالَ جَاءَ رَجُلٌ إِلَى رَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ مِنْ أَهْلِ نَجْدٍ ثَائِرَ الرَّأْسِ يُسْمَعُ دَوِيُّ صَوْتِهِ وَلاَ يُفْقَهُ مَا يَقُولُ حَتَّى دَنَا فَإِذَا هُوَ يَسْأَلُ عَنِ الإِسْلاَمِ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ خَمْسُ صَلَوَاتٍ فِي اليَوْمِ وَاللَّيْلَةِ فَقَالَ هَلْ عَلَيَّ غَيْرُهَا قَالَ لاَ إِلَّا أَنْ تَطَوَّعَ قَالَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ وَصِيَامُ رَمَضَانَ قَالَ هَلْ عَلَيَّ غَيْرُهُ قَالَ لاَ إِلَّا أَنْ تَطَوَّعَ وَذَكَرَ لَهُ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ الزَّكَاةَ قَالَ هَلْ عَلَيَّ غَيْرُهَا قَالَ لاَ إِلَّا أَنْ تَطَوَّعَ فَأَدْبَرَ الرَّجُلُ وَهُوَ يَقُولُ وَاللَّهِ لاَ أَزِيدُ عَلَى هَذَا وَلاَ أَنْقُصُ قَالَ رَسُولُ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ أَفْلَحَ إِنْ صَدَقَ
46 صحيح البخاري كتاب الإيمان باب الزكاة من الإسلام
11 صحيح مسلم كتاب الإيمان باب بيان الصلوات التي هي أحد أركان الإسلام