A.T. Robertson Commentary Luke 14:29

"Lest haply, when he hath laid a foundation, and is not able to finish, all that behold begin to mock him," — Luke 14:29 (ASV)

Lest haply (ινα μηποτε). Double final particles (positive and negative with addition of ποτε). Used here with aorist middle subjunctive in αρξωντα (begin).

When he hath laid... and was not able (θεντος αυτου... κα μη ισχυοντος)

to finish (εκτελεσα). First aorist active infinitive. Note perfective use of εκ, to finish out to the end. Two genitive absolutes, first, second aorist active participle θεντος; second, present active participle ισχυοντος.

To mock him (αυτω εμπαιζειν). An old verb, εμ-παιζω, to play like a child (παις), at or with, to mock, scoff at, to trifle with like Latin illudere.