Juro decir la verdad.

Juro is the 1st person singular present indicative of jurar, so it means I swear.

A quick breakdown:

• jurar = to swear
• juro = I swear

In this sentence, the speaker is making the oath right now.

Because Spanish often drops subject pronouns when the verb ending already shows who the subject is.

• juro already tells us the subject is I
• so Juro decir la verdad is perfectly natural

You could say Yo juro decir la verdad, but that usually adds emphasis, contrast, or formality.

Because Spanish commonly uses the pattern jurar + infinitive to mean to swear to do something.

So:

• juro = I swear
• decir = to tell / to say

Together, juro decir means I swear to tell.

This is similar to other Spanish patterns:

• quiero comer = I want to eat
• prometo ayudar = I promise to help
• juro decir = I swear to tell

Because after jurar, Spanish does not use a preposition here.

In English, we say I swear to tell the truth, with to before tell.
But in Spanish, the infinitive can go directly after the verb:

• Juro decir la verdad

So even though English has to, Spanish does not add a in this structure.

Because the normal expression is decir la verdad = to tell the truth.

This is a fixed, very common phrase. In Spanish, abstract nouns often use the definite article where English may or may not.

So:

• decir la verdad = to tell the truth
• decir verdad sounds unusual in standard modern Spanish

You need decir, not hablar, because decir la verdad means to tell the truth.

• decir = to say / to tell
• hablar = to speak / to talk

So:

• decir la verdad = to tell the truth
• hablar la verdad is not the normal expression

English learners often want to match speak and tell, but Spanish uses specific expressions, and here the correct one is decir la verdad.

Yes, but it means something a little different.

• Juro decir la verdad = I swear to tell the truth
• Juro que digo la verdad = I swear that I am telling the truth / I swear I tell the truth

The first is an oath or promise about what the speaker will say.
The second is more a statement about the truthfulness of what the speaker is saying.

So if you are thinking of a courtroom-style oath, Juro decir la verdad is the better match.

Yes, it is quite formal and sounds like an official oath.

You might hear it in contexts like:

• court
• legal proceedings
• ceremonies
• official declarations

In everyday conversation, people are more likely to say things like:

• Te lo juro = I swear
• Te juro que es verdad = I swear it’s true

So Juro decir la verdad sounds serious and institutional.

In standard Peninsular Spanish, approximately:

• juro → HOO-roh
• decir → deh-THEER
• la verdad → lah behr-DATH or lah vehr-DAH depending on speaker

A few key Spain-specific points:

• j is a strong throaty sound, not an English j
• the c in decir before i is pronounced like th in think in most of Spain
• final d in verdad is often softened in natural speech

So decir in Spain is typically deh-THEER, not deh-SEER.

Not naturally in this case. Juro decir la verdad is the standard order.

Why?

• juro is the main verb
• decir la verdad is its complement

Putting it in another order would sound marked, poetic, or unnatural in normal speech.

So for learners, the safe pattern is:

• Juro + infinitive
• Juro decir la verdad

Yes. It is a complete sentence.

Even though it is short, it has everything it needs:

• an implied subject: I
• a conjugated verb: juro
• a verbal complement: decir la verdad

It works especially well as a fixed oath formula, where short, direct wording is normal.