Prophet (saas) said: "Your Lord is Kind and Most Generous, and is too kind to let His slave, if he raises his hands to Him, bring them back empty," or he said "frustrated."  

عَنِ النَّبِيِّ ﷺ قَالَ إِنَّ رَبَّكُمْ حَيِيٌّ كَرِيمٌ يَسْتَحْيِي مِنْ عَبْدِهِ أَنْ يَرْفَعَ إِلَيْهِ يَدَيْهِ فَيَرُدَّهُمَا صِفْرًا أَوْ قَالَ خَائِبَتَيْنِ  

the Messenger of Allah (saas) said: "When you supplicate to Allah, supplicate with your palms uppermost, not with the backs of your hands uppermost, and when you finish, wipe your face with them."  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا دَعَوْتَ اللَّهَ فَادْعُ بِبُطُونِ كَفَّيْكَ وَلاَ تَدْعُ بِظُهُورِهِمَا فَإِذَا فَرَغْتَ فَامْسَحْ بِهِمَا وَجْهَكَ