يَقُولُ يَـٰلَيْتَنِى قَدَّمْتُ لِحَيَاتِى
Sentence structure
يَقُولُ is the result linked to the preceding time clause, with understood subject هُوَ. يَـٰلَيْتَنِى opens a wish construction: attached نِى is the noun of لَيْتَ, and قَدَّمْتُ its predicate clause.
Ayah summary
He will regretfully say that he wishes he had sent good deeds ahead for his true life.
يَقُولُ — He will say
Grammar: A third-person masculine-singular indicative imperfect with understood subject هُوَ, functioning as the response to the earlier time condition.
يَـٰلَيْتَنِى — O I wish
Grammar: يَا alerts, لَيْتَ is a particle of wish and accusative, نِ protective nūn, and attached ى its noun.
قَدَّمْتُ — I had sent forth
Grammar: A Form II first-person singular perfect; attached تُ is the subject, and the clause is the predicate of لَيْتَ.
لِحَيَاتِى — for my life
Grammar: لِ is a preposition; حَيَاتِ is its feminine genitive noun and attached ى a genitive possessor. This phrase is linked to «قَدَّمْتُ».