This is the overarching question of the whole "the Qur'an is not enough" debate. Some circles say, "the Qur'an alone is not enough; not just to live by, but even to understand Islam you need hadith and sīra; the Qur'an is obscure / deficient." So what does the Book's own witness say?
1) The Qur'an deems itself complete
- "We have neglected nothing in the Book." (6:38)
- "We sent down to you the Book as a clarification of all things (tibyān)." (16:89)
- "This is no invented tale, but a detailed exposition of everything." (12:111)
- "We have given in this Qur'an every kind of example for people." (18:54; 39:27)
2) The Qur'an deems itself clear and intelligible
The real claim is "not enough to understand." Yet the Qur'an speaks precisely about being understood:
- "He sent down to you the Book clearly explained (mufaṣṣal)." (6:114); "its verses were made firm, then detailed." (11:1)
- "We have made the Qur'an easy to understand." — four times in one sūra (54:17, 22, 32, 40).
- "We made it an Arabic Qur'an so you may reason." (12:2; 43:3)
- "Do they not reflect upon the Qur'an?" (4:82; 47:24) — addressed directly to the human and the intellect.
3) God takes the clarifying upon Himself
- "Then its clarification (bayān) is upon Us." (75:19)
- "In every example, We bring you the truth and the best explanation (tafsīr)." (25:33)
The logical result — and the false dilemma
To say "it is not enough even to understand, it is deficient" directly contradicts the witness above: "I am clear, made easy, reflect upon Me, My clarification is upon Me."
But the dilemma "either God lied, or the groups lie" is falsely framed. The third, correct option is:
- "Explains everything" = explains its religion completely and intelligibly; it does not mean "contains every technical/daily detail (a recipe, a rakʿah count)."
- Hadith/sīra can be an aid, a context (like occasions of revelation) — that is legitimate and does not contradict the text.
- The only thing that contradicts is raising this to "the Qur'an cannot be understood without it / is deficient." "It helps" is one thing; "without it, it is deficient" is another.
The verse "We sent down the Reminder that you may clarify it to people" (16:44) does not overturn this either: the Prophet's clarifying is the conveying and lived application of the revelation; where God Himself takes on the Qur'an's clarification (75:19), the conclusion "a separate, necessary source is required" is an interpretation, not the wording of the text.
An honest limit
At the level of the text, what is clear: the Qur'an deems itself clear, made easy, and complete (6:38; 6:114; 54:17; 75:19). At the level of interpretation, what is contested: the scope of "obey the Messenger" and "clarify" (→ Does "obey the Messenger" bind hadith?). We declare no one a "liar"; we weigh the claim by the Book's own witness. The groups' concern for transmission is understandable; but the wording "the Qur'an is deficient / unintelligible" is incompatible with the Qur'an's own statements.
Source: Qur'anic verses (M. Okuyan meal). Presented soberly and respectfully, with a text/interpretation distinction.