Matsya Purana 258.19

258.19

tadaṣṭakena likṣā tu yūkālikṣāṣṭakairmatā.
yavo yūkāṣṭakaṃ tadvadaṣṭabhistaistadaṃgulam.. 258.18

The image with eight hands should be made to hold a sword a club an arrow and a lotus in the right hands and a bow a shield a conch and a quoit in the left hands The image with four hands should be made to hold a club and a lotus in the right hands and a conch and a quoit in the left hands Thus persons desirous of wealth and opulence should follow with regard to the four-armed Viṣṇu—7 9 front and the breadth of the centre of the knees is 21 fingers, their height is 1 finger and their circumference should be three fingers—50-54