 Patanjali's "Yogasutra", in verse II.44, recommends "Svadhyaya" as follows

Vishnu Smriti's verse 22.92, states that "human body is cleansed by water, the mind is cleansed by truth, the soul by self-study and meditation, while understanding is cleansed by knowledge".Vasistha Dharmasastra verses 27.1 through 27.7 states that "Svadhyaya" helps an individual understand and overcome his past.Apastamba Dharmasutra 1.4.12.1 states "Svadhyaya" is a form of "Tapas".