Is it permissible for a brother to give a gift to his sister to the exclusion of his other siblings?

The restriction regarding favoritism among those gifted applies only to children, based on the hadith: "Fear Allah and be just among your children." As for siblings, some scholars hold the view that justice among them is sunnah (recommended), while Ibn Qudamah weakened the opinion of its being obligatory. Al-Shirbini stated that this ruling does not apply to siblings and their like, and equality among them is desirable, but not as strongly required as it is for ascendants and descendants.