Muwatta Malik 453
موطأ مالك#453Mawdu'Yahya related to me from Malik that he had heard that the Messenger of Allah, may Allah bless him and grant him peace, used to say, "When a cloud appears from the direction of the sea and then goes towards ash-Sham, it will be an abundant source of rain
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Salim al-HilaliMawdu
In-book reference: 13:5