I speak as to children.
τὴν δὲ αὐτὴν ἀντιμισθίαν, ὡς τέκνοις λέγω, πλατύνθητε καὶ ὑμεῖς.
Paul said that in return (τὴν δὲ αὐτὴν ἀντιμισθίαν), I speak (λέγω) as to children (ὡς τέκνοις). Open wide your hearts (πλατύνθητε καὶ ὑμεῖς)! Only the Pauline letters used this word ἀντιμισθίαν, that means a reward, recompense, or retribution. Paul indicated that he would respond or reward the Corinthians by speaking to them as they were his children. He just wanted them to open up their hearts, since Paul was their spiritual father. Like good children, he wanted them to listen with an open heart to what he was saying. This was both an affection and a reprimand. He loved them as children, but they were acting like children. They had to be more attentive to what he was saying. Do you treat people like children?