Muwatta Malik 1071

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ رَبِيعَةَ بْنِ أَبِي عَبْدِ الرَّحْمَنِ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ بْنِ الْحَارِثِ التَّيْمِيِّ، أَنَّهُ قَالَ سَمِعْتُ أَبِي يَسْتَحِبُّ الْعَقِيقَةَ، وَلَوْ بِعُصْفُورٍ ‏.‏

Yahya related to me from Malik from Rabia ibn Abi Abd ar-Rahman that Muhammad ibn Ibrahim ibn al-Harith at-Taymi said, "I heard my father say that the aqiqa was desirable, even if it was only a sparrow

Reference

Muwatta Malik 1071

In-book

Book 26, Hadith 5