Skandapurana 5.198.65

5.198.65

dave karmaṇi pitrye vā somapāne viśeṣataḥ..
deśāṃtaragato yastu śrāddhaṃ ca kurute naraḥ ..
vaiśvānarapurastena kāryaṃ nānyadvijasya ca .. 65..

In a rite for the gods or for the ancestors, especially at the drinking of soma— / but a man who has gone to another country and performs a śrāddha / must perform it before Agni, and not with another twice-born.