Full Arabic — click to listen
wal-samāi
By the sky
P – prefixed preposition wa (oath) + DET – determiner prefix al + N – genitive feminine noun 
Root Link: س م و
wal-ṭāriqi
and the night comer
CONJ – prefixed conjunction wa (and) + DET – determiner prefix al + N – genitive masculine active participle
Root Link: ط ر ق

Acknowledgements:

Single-Word Audio has been made possible through software provided by Arabic NLP

James Ada's concordance work; his research can be found at www.organizedQuran.com
Note: James is now a member of the IslamAwakened Continuity Board