Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said concerning this verse: "And stand before Allah in devout obedience" [Surah al-Baqarah: 238], he said: "They used to talk during the prayer; a man's servant would come to him while he was in the prayer and speak to him about his need, so they were forbidden from talking."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 11726