After salam

اللَّهُمَّ إِنِّي أَسْأَلُكَ عِلْماً نافِعاً وَرِزْقاً طَيِّباً وَعَمَلاً مُتَقَبَّلاً (بَعْدَ السّلامِ مِنْ صَلاَةِ الفَجْرِ)

"O Allah, I ask You for knowledge which is beneficial, and sustenance which is good, and deeds which are acceptable."

Ibn Majah and others. See Sahih Ibn Majah 1/152 and Majma' Az-Zawa'id 10/111