Short answer. The vendor must deliver the thing sold, with its accessions and accessories, in the condition it was in when the contract was perfected — not some later or earlier state. And the buyer becomes entitled to all fruits starting from that same date, the day the contract itself was perfected.
What the law says
The vendor is bound to deliver the thing sold and its accessions and accessories in the condition in which they were upon the perfection of the contract.
Civil Code, Article 1537 — Condition of the Thing; Fruits. Read the full provision →
What the law says
All the fruits shall pertain to the vendee from the day on which the contract was perfected.
Civil Code, Article 1537 — Condition of the Thing; Fruits. Read the full provision →
The condition-at-perfection rule
Article 1537 fixes the reference point for the physical state of what is delivered: the vendor must hand over the thing sold, together with its accessions and accessories, in the condition in which they were upon the perfection of the contract. The relevant moment is not delivery itself, and not the time the sale was first discussed, but specifically when the contract was perfected — meaning when the parties actually reached agreement.
Accessions and accessories travel with the thing
The obligation is not limited to the thing sold in isolation. Article 1537 extends it to accessions and accessories as well, so whatever had attached to or normally went along with the item at the time the contract was perfected has to be delivered along with it, in that same condition, not stripped away or substituted for something else once the vendor finally hands the property over.
Fruits belong to the buyer from the day the contract was perfected
Article 1537's second sentence answers when the buyer's right to fruits begins: all the fruits shall pertain to the vendee from the day on which the contract was perfected. This ties entitlement to fruits to the same date used for the condition of the thing, so the buyer's rights over what the property produces start running from perfection, not from whenever physical delivery actually happens to occur afterward, however much later that turns out to be.
Why the perfection date, rather than delivery, is what counts
Using perfection as the fixed point for both the thing's condition and the buyer's right to fruits means the buyer is protected against a gap between agreeing to the sale and physically receiving the property. Even if delivery is delayed for some time, the buyer's entitlement to fruits produced in the meantime is not lost, and the vendor cannot use the passage of time before delivery to justify handing over the item in a worse condition than it was in when the parties originally struck their agreement.