The Prophet ﷺ said, "Your Lord is Huyayy and Generous. He is too modest to let His servant raise his hands to Him and then turn them back empty," or he said, "disappointed."
حدثنا أبو بشر بكر بن خلف حدثنا ابن أبي عدي عن جعفر بن ميمون عن أبي عثمان
عن النبي ﷺ قال إن ربكم حيي كريم يستحيي من عبده أن يرفع إليه يديه فيردهما صفرا أو قال خائبتين
Sourcing, hasan. Reported by Abu Dawud, Prayer, chapter on supplication, no. 1488, from the hadith of Jafar, and the majority graded it daif, yet Tirmidhi graded it hasan, no. 3556, and Ibn Hibban graded it sahih, no. 2400. The mawquf version is more sound, and the hadith has supporting narrations.