Imam al-Shafi'i (may Allah have mercy on him) said: "We know of no one among people, except very few, who has pure obedience and decency without mixing them with any sin or abandonment of decency; nor is there anyone who has pure sin and abandonment of decency without any mixture of obedience and decency."
The Shaykh (Imam al-Bayhaqi) (may Allah have mercy on him) said: "It is just as Imam al-Shafi'i (may Allah have mercy on him) said."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الشهادات / Q20742