Baudhayanadharmasutra 4.4.1

4.4.1

prāyaścittāni (vakṣyāmo 'vikhyātāni viśeṣataḥ /
samāhitānāṃ yuktānāṃ pramādeṣu kathaṃ (bhavet //

We will explain the (secret) penances which are not prescribed (by others, but by the offender himself, and) particularly what shall be done in (case) faults (have been committed) by men who, with concentrated minds, (are) intent (on the performance of their duties).