كتاب الزكاة
Obligatory Charity Tax (Zakat)
Chapter: The Statement of Allah 'Azza wa Jall: "... They do not beg people persistently. ..." (2:273) And who may be considered to have enough to be content and abstain from begging"
بَابُ قَوْلِ اللَّهِ تَعَالَى: {لاَ يَسْأَلُونَ النَّاسَ إِلْحَافًا} وَكَمِ الْغِنَى
Sahih al-Bukhari 1479

Narrated Abu Huraira:

Allah's Messenger (ﷺ) said, "The poor person is not the one who goes round the people and ask them for a mouthful or two (of meals) or a date or two but the poor is that who has not enough (money) to satisfy his needs and whose condition is not known to others, that others may give him something in charity, and who does not beg of people."

حَدَّثَنَا إِسْمَاعِيلُ بْنُ عَبْدِ اللَّهِ، قَالَ حَدَّثَنِي مَالِكٌ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ لَيْسَ الْمِسْكِينُ الَّذِي يَطُوفُ عَلَى النَّاسِ تَرُدُّهُ اللُّقْمَةُ وَاللُّقْمَتَانِ وَالتَّمْرَةُ وَالتَّمْرَتَانِ، وَلَكِنِ الْمِسْكِينُ الَّذِي لاَ يَجِدُ غِنًى يُغْنِيهِ، وَلاَ يُفْطَنُ بِهِ فَيُتَصَدَّقُ عَلَيْهِ، وَلاَ يَقُومُ فَيَسْأَلُ النَّاسَ ‏"‏‏.‏
Reference : Sahih al-Bukhari 1479
In-book reference : Book 24, Hadith 80
USC-MSA web (English) reference : Vol. 2, Book 24, Hadith 557
  (deprecated numbering scheme)