Allah, the Blessed and Exalted, says: "So eat of them and feed the distressed poor." [Surah al-Hajj: 28]
And He said: "And feed the one who is content and the one who asks." [Surah al-Hajj: 36]
Imam al-Shafi'i (may Allah have mercy on him) said: "Al-qani' is the one who asks, and al-mu'tarr is the visitor and the one who passes by at no fixed time."
And in another place he said: "Al-qani' is the poor person and al-mu'tarr is the visitor; and it has been said that (al-mu'tarr) is the one who presents himself to receive a gift from it (the sacrifice)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / Q19223