Sa’ari, C. Z. “A Purification of Soul According to Sufis: A Study of Al-Ghazali’s Theory”. Afkar: Jurnal Akidah Dan Pemikiran Islam, vol. 3, no. 1, June 2002, pp. 95-112, https://mojc.um.edu.my/index.php/afkar/article/view/6020.