ENOfficial
Narrated Abdullah ibn Abbas: Ikrimah quoted Ibn Abbas as saying: When asking for something you should raise your hands opposite to your shoulders; when asking for forgiveness you should point with one finger; and when making an earnest supplication you should spread out both your hands.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُوسَى بْنُ إِسْمَاعِيلَ، حَدَّثَنَا وُهَيْبٌ، - يَعْنِي ابْنَ خَالِدٍ - حَدَّثَنِي الْعَبَّاسُ بْنُ عَبْدِ اللَّهِ بْنِ مَعْبَدِ بْنِ الْعَبَّاسِ بْنِ عَبْدِ الْمُطَّلِبِ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ الْمَسْأَلَةُ أَنْ تَرْفَعَ، يَدَيْكَ حَذْوَ مَنْكِبَيْكَ أَوْ نَحْوَهُمَا وَالاِسْتِغْفَارُ أَنْ تُشِيرَ بِأُصْبُعٍ وَاحِدَةٍ وَالاِبْتِهَالُ أَنْ تَمُدَّ يَدَيْكَ جَمِيعًا .
sunnah.com