The Law Code of Devala 22

22

ūrdhvaṃ saṃvatsarātkalpyaṃ prāyaścittaṃ dvijottamaiḥ
saṃvatsaraiścaturbhiśca tadbhāvamadhigacchati

Beyond a year, a penance is to be prescribed by the best of the twice-born; / and after four years he assumes that [Mleccha] nature.