Etiquette with Siblings
A Muslim is of the view that manners with one's siblings should be like manners with one's parents and children. For example, the smaller sibling should relate toward his elder sibling like a child with his father, the elder sibling should relate to his younger siblings like parents to their children, with respect to obligations and manners. This is based on what has been narrated:
'The right of the elder sibling over the younger sibling is like the right of the father over his child.' (Al-Bayhaqi and it is weak)
Allah's Messenger (S.A.W.S.) also said:
'Be dutiful towards your mother and your father, and your sister and your brother, then those closest to you, followed by those next to you.' (Al-Hakim and the basis of it is in the Sahih and the Sunan.)