“Once, a man complained before abu ‘Abd Allah (a.s.), about cracks in his hands and feet. He (the Imam) said, ‘Take a piece of cotton, place frankincense oil in it and apply it in your belly button.’ Ishaq ibn ‘Ammar has said that I said, ‘I pray to Allah to keep my soul in service for your cause, frankincense oil in cotton, then in his belly button?’ He (the Imam) said, ‘O Ishaq, to pour frankincense oil in your belly button it is a great task.’ Ibn ‘Udhaynah has said, ‘Thereafter I met the man. He informed me that he followed the instruction only once and his problems went away.’”