Manasara 12.73

12.73

hemajaṃ yajñasūtraṃ syādoṅkārasyopari nyaset
svastikādīni varṇena caturdikṣu vinikṣipet

a sacrificial thread made of gold should be placed above the syllable Om. / One should deposit svastikas and the like of the [appropriate] colour in the four cardinal directions;