Skandapurana 16.207.13

16.207.13

sāgraṃ māsaṃ raveḥ krāntāvādyaśrāddhe trivatsaram ..
māsike'pyatha varṣasya ṣaṇmāse tvardhavatsaram .. 13 ..

A full month at the transit of the sun; at the initial śrāddha, three years; / At the monthly rite, a year; at the six-monthly, half a year;