We have synthesized and characterized the physical properties of a layered, mixed valent oxypnictide \({\textrm{La}_\textrm{3}\textrm{Cu}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) via magnetization, electrical resistivity, and specific heat measurements. Although \({\textrm{La}_\textrm{3}\textrm{Cu}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) does not exhibit superconductivity down to T = 0.5 K, it demonstrates an intriguing resistivity minimum observed at \(\mathrm {T_{min}}\) = 13.7 K. Disappearance of the resistivity minimum under an applied magnetic field of \(\mu _0\) H = 9 T together with the negative magnetoresistance at low and positive at high temperatures are observed, which are typical for both Kondo-like spin-dependent scattering and 3D weak localization. We argue that the Kondo scattering is a more plausible explanation due to the low-temperature deviation from the Curie-Weiss law observed in the magnetic susceptibility, consistent with the presence of magnetic interactions between paramagnetic \({\textrm{Cu}^{2+}}\) ions and Kondo screening of these \({\textrm{Cu}^{2+}}\) moments. We supplemented the experimental characterization with a detailed description of chemical bonding, employing density functional theory (DFT) calculations and crystal orbital Hamilton population (COHP) analysis for \({\textrm{La}_\textrm{3}\textrm{Cu}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) and isostructural \({\textrm{La}_{3}\textrm{Ni}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) , which is a superconductor with \(\mathrm {T_c} = 2.2\) K. Based on the calculations performed, we present the difference between \({\textrm{La}_\textrm{3}\textrm{Cu}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) and \({\textrm{La}_{3}\textrm{Ni}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) in the character of electronic states at the Fermi level. This discrepancy impacts structural stability and may cause a lack of superconductivity in \({\textrm{La}_\textrm{3}\textrm{Cu}_{4}\textrm{P}_{4}\textrm{O}_{2}}\) down to T = 0.5 K.
