Hadithcore
Al-Adab Al-Mufrad, 60
sahih· Al-Albani

It is reported that al-Miqdam ibn Ma'dikarib heard the Messenger of Allah, (ﷺ), say, "Allah enjoins you to be dutiful to your mothers. Then He enjoins you to be dutiful to your mothers. Then He enjoins you to be dutiful to your fathers. Then He enjoins you to be dutiful to your next closest relative and then to your next closest relative."

حَدَّثَنَا حَيْوَةُ بْنُ شُرَيْحٍ، قَالَ‏:‏ حَدَّثَنَا بَقِيَّةُ، عَنْ بَحِيرٍ، عَنْ خَالِدِ بْنِ مَعْدَانَ، عَنِ الْمِقْدَامِ بْنِ مَعْدِي كَرِبَ، أَنَّهُ سَمِعَ رَسُولَ اللهِ صلى الله عليه وسلم يَقُولُ‏:‏ إِنَّ اللَّهَ يُوصِيكُمْ بِأُمَّهَاتِكُمْ، ثُمَّ يُوصِيكُمْ بِأُمَّهَاتِكُمْ، ثُمَّ يُوصِيكُمْ بِآبَائِكُمْ، ثُمَّ يُوصِيكُمْ بِالأَقْرَبِ فَالأَقْرَبِ‏.‏

References2 variants
In-Book Reference
Book 2, Hadith 14
English Reference
Book 2, Hadith 60