Hadith 769
Chapter 272: The Supplication With Which The Prayer Should Be Started - كتاب الصلاة
حَدَّثَنَا الْقَعْنَبِيُّ، عَنْ مَالِكٍ، قَالَ لاَ بَأْسَ بِالدُّعَاءِ فِي الصَّلاَةِ فِي أَوَّلِهِ وَأَوْسَطِهِ وَفِي آخِرِهِ فِي الْفَرِيضَةِ وَغَيْرِهَا .
Malik said:
There is no harm in uttering supplication in prayer, in its beginning, in its middle, and in the end, in obligatory prayer or other.
Reference : Sunan Abi Dawud 769
In-book reference : Book 2, Hadith 379