What is the ruling on jealousy stemming from parents favoring one child over others in treatment and affection, and what is the way to control this feeling?

The Shari'ah commanded justice among children and forbade preferring some over others, lest grudges and enmity arise. Scholars have recommended equality among them even in minor matters like a kiss. The Shari'ah also forbade envy, and its cure lies in reflecting upon its ugliness and striving to treat the envied person with kindness. If envy leads to disparagement, arrogance, or withholding blessings from the envied person, one should deliberately do the opposite: praise, show humility, and increase blessings upon them. This brings about the love of the envied person and eradicates the root of envy.