Source of quotation from Buddhaghosa about Buddha being trackless

Radhakrishnan's edition of The Dhammapada provides the following quotation from Buddhaghosa as a commentary on Verse 179 (Chapt, 14, 1 Buddhavagga) where the Buddha is described as *apadam* trackless/signless: > "The man who is possessed of even a single one of such conditions as > *raga*, attachment, &c., him ye can lead forward; but the Buddha has not even one condition or basis of renewed existence, and therefore by > what track will you lead this unconditioned Buddha?" Could anyone tell me the source of this quotation and also provide me with the Pali?