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第五百二十三条 当事人约定由第三人向债权人履行债务，第三人不履行债务或者履行债务不符合约定的，债务人应当向债权人承担违约责任。
Article 523
Where the parties agree that the obligation shall be performed by a third person
to the creditor, if the third person fails to perform the obligation or the
performance does not conform to the agreement, the debtor shall bear default
liability to the creditor.
第五百二十四条 债务人不履行债务，第三人对履行该债务具有合法利益的，第三人有权向债权人代为履行；但是，根据债务性质、按照当事人约定或者依照法律规定只能由债务人履行的除外。
Article 524
Where a debtor fails to perform an obligation and a third person has a lawful
interest in the performance of the obligation, the third person is entitled to
perform it to the creditor on behalf of the debtor, unless the obligation may
only be performed by the debtor based on the nature of the obligation, as agreed
by the parties, or as provided by law.
债权人接受第三人履行后，其对债务人的债权转让给第三人，但是债务人和第三人另有约定的除外。
After the creditor accepts the performance of such obligation by the third
person, his claim against the debtor shall be assigned to the third person,
unless otherwise agreed by the debtor and the third person.
第五百二十五条 当事人互负债务，没有先后履行顺序的，应当同时履行。一方在对方履行之前有权拒绝其履行请求。一方在对方履行债务不符合约定时，有权拒绝其相应的履行请求。
Article 525
Where the parties mutually owe obligations to each other and the contract does
not provide for a priority order of performance, the parties shall concurrently
perform their obligations. Either party may reject the other party’s request for
performance before the other party performs. Either party may reject the other
party’s request for the corresponding performance if the other party’s
performance does not conform to the agreement.
第五百二十六条 当事人互负债务，有先后履行顺序，应当先履行债务一方未履行的，后履行一方有权拒绝其履行请求。先履行一方履行债务不符合约定的，后履行一方有权拒绝其相应的履行请求。
Article 526
Where the parties mutually owe obligations to each other and the contract
provides for a priority order of performance, if the party obligated to perform
first fails to perform the obligation, the party obligated to perform later may
reject the request for performance made by that party. Where the performance of
the party obligated to perform first does not conform to the agreement, the
party obligated to perform later may reject the request made by the former party
for performance of the corresponding obligation.
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