Abu Amr al-Shaybani narrates from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: In the time of the Messenger of Allah (peace and blessings be upon him), when we were in the prayer and one of us needed something, he would speak to his companion and whisper to him quietly, until this verse was revealed: "And stand before Allah in devout obedience" [al-Baqarah: 238], and we were ordered to keep silent.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5045