Al-Kāfi

Hadith 1784
temporary-marriage
3- مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ ابْنِ مَحْبُوبٍ عَنِ ابْنِ رِئَابٍ عَنْ زُرَارَةَ بْنِ أَعْيَنَ قَالَ قُلْتُ مَا يَحِلُّ مِنَ الْمُتْعَةِ قَالَ كَمْ شِئْتَ.
3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ibn Mahbub from ibn Ri’ab from Zurarah ibn ‘A‘yan who has said the following: “I once asked him (the Imam) (a.s.), ‘How many is lawful for al-Mut‘ah (advantageous marriage)?’ He (the Imam) said, ‘It is as many as you wish.’”
Source: Shaykh Muḥammad b. Yaʿqūb al-Kulaynī