"Rehabilitation" (リハビリ, Rihabiri) is chapter 603 of the original Naruto manga.
Left to the company of White Zetsu and another with a spiral-like facial pattern, Obito becomes thoroughly annoyed at the duo, who are fascinated with how human bodily functions work — not having the need themselves to eat, drink, or even use the bathroom. Telling them not to lump him in with their lot, Obito notes that only half of him was made of artificial material. Stating that they were supposed to help Obito with his rehabilitation until Madara woke up, the duo began to question Obito about why he kept repeating a bell sound and "stupid Kakashi" in his sleep. After explaining that the third clone had gone outside to gather information and that they were able to move through the earth, the two Zetsu begin to recite Madara's plans for world peace. Disregarding this, Obito once again states his resolve to leave this place and join Rin and Kakashi, thus began his painful rehabilitation. After what seemed to be a fair amount of time passing, Obito, whose hair had noticeably grown longer, was able to use the artificial limbs perfectly. One day, White Zetsu returned to the hideout and alerted Obito that his comrades were in danger, surrounded by Kirigakure shinobi. Leaping into action, Obito tried to break out of the cave, but only managed to crack the rock and tear off his right arm. The spiral-patterned Zetsu offered up himself as a suit of sorts and encases the young Uchiha, who prepares to head out.