Garudapurana 2.5.68

2.5.68

dvitīyañca tato mārge viśrāmo yatra kāritaḥ /
tataḥ sañcayanasthāne tṛtīyaṃ śrāddhamucyate //

And the second [is performed] on the road, wherever a rest was made; / then at the place where the bones are collected, the third śrāddha is said [to be done].