Mishkat al-Masabih, hadith 2144

وَعَنْ مَالِكِ بْنِ يَسَارٍ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا سَأَلْتُمُ اللَّهَ فَاسْأَلُوهُ بِبُطُونِ أَكُفِّكُمْ وَلَا تَسْأَلُوهُ بِظُهُورِهَا» وَفِي رِوَايَةِ ابْنِ عَبَّاسٍ قَالَ: «سَلُوا اللَّهَ بِبُطُونِ أَكُفِّكُمْ وَلَا تَسْأَلُوهُ بِظُهُورِهَا فَإِذَا فَرَغْتُمْ فامسحوا بهَا وُجُوهكُم» . رَوَاهُ دَاوُد

Malik b. Yasar reported God’s messenger as saying, “When you make requests of God, do so with the palms of your hands and not the backs upward.” In the version of Ibn ‘Abbas he said, “When you make requests of God, do so with the palms of your hands and not the backs upward, and when you are finished wipe your faces with them.” Abu Dawud transmitted it.