20-4-5. Indivisible obligation partially extinguished by partial performance if benefit voluntarily retained--Exception.
A partial performance of an indivisible obligation extinguishes a corresponding proportion thereof, if the benefit of such performance is voluntarily retained by the creditor, but not otherwise. If such partial performance is of such a nature that the creditor cannot avoid retaining it, without injuring his own property, his retention thereof is not presumed to be voluntary.
Source: CivC 1877, §831; CL 1887, §3455; RCivC 1903, §1148; RC 1919, §755; SDC 1939, §47.0205.