So the one who desires to strengthen his spirituality and wants to acquire Nafs-e-Mutma-innah should slaughter the rooster – meaning to kill his lust, should slaughter the peacock – meaning he should kill the pride of his personality and attire, he should slaughter the vulture – meaning he should kill his greed and he should slaughter the pigeon – meaning he should kill the feeling of being proud of his high worldly status. If someone succeeds in killing and slaughtering these four ill traits, he will observe the revival of his heart with his own eyes and will be blessed with the wealth of ‘Nafs-e-Mutma-innah’.
(I’afseer Jamal, vol. 1, pp. 328; part 2, Surah AI-Baqarah, Ayah 260)