Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "On Friday there is an hour in which no one gets cupped except that a disease afflicts him from which he is not cured."
Attaf bin Khalid is da'if (weak). Yahya bin al-Ala al-Razi, who is matruk (abandoned), narrated a marfu' hadith about it with a chain of his from al-Husayn bin Ali, and it is worthless.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19541