upasarpanam

upasarpaṇam the approaching; SB 3.14.15
vaikuṇṭha-pāda-mūla-upasarpaṇam the approaching of the shelter of Lord Viṣṇu's lotus feet; SB 6.17.14
pāda-upasarpaṇam approaching the lotus feet; SB 7.6.2
pada-upasarpaṇam worship of the lotus feet; SB 8.24.30