In the Hadiqat al-Haqiqah, Sana'i extends his critique of biological kinship to sisters, viewing their presence through a lens of material and social anxiety. He argues that the birth of a sister causes distress to the father due to the requirements of inheritance and the provision of a dowry (jahiz). Sana'i suggests that the biological sister, driven by desires for marriage and material wealth, represents a potential for familial dishonor and a distraction from spiritual focus. This thematic focus reinforces his broader ascetic message that blood relations are often obstacles to spiritual sincerity.